Choosing a Linux Distribution
Now we've gotten to the fun part. You've read about what the differences between distributions are and why they exist at a higher level, now it's time to actually get your hands dirty.
If you don't want to listen to me yap, my primary recommendation is this: Use what's popular. Using a popular distro will mean that there is a lot of information out there regarding fixing potential problems. It also means that there is a wide userbase that can and will provide support. Finally, larger distros tend to have larger, more active dev teams, meaning issues or vulnerabilities will be patched quickly.
This leads to my other primary recommendation: Join communities/chats related to your distro. Most widely used distros have a Discord, forum, or some other chat you can join. You should join that. Discord and IRC in particular can help you get support quickly, since there's usually knowledgable people hanging around. (Though if you don't want to spend time there for anything besides support, I don't blame you.) Joining these communities also ensures you get updates about what's going on with your distro and in the Linux community in general.
When asking for support, always remember to be polite and state your problem clearly. Provide relevant information when requested. And remember, don't ask to ask, just ask.
Good Beginner Distributions
These are the distributions that I would actually recommend to people who have never used Linux at all, and want to dip their toes in. These distributions focus on working out of the box, being able to be configured graphically as opposed to needing the terminal for some things. (You can still use the terminal if you want, though!) You might've heard of at least some of these.
Linux Mint
https://www.linuxmint.com
Based on Debian/Ubuntu
More Info ⮝
This is one of the most widely recommended distros for beginners, and for good reason. Linux Mint's goal is to present an experience that users will be able to use out of the box. Its desktop, Cinnamon, will feel right at home to Windows users, as it presents a familiar, polished desktop and lots of graphical utlilties for configuring the system and installing applications. Due to being based off Ubuntu and therefore Debian, users can enjoy widespread support. Anecdotally speaking, Mint was the first distribution that I used for a large amount of time, and I enjoyed it immensely. So, if you need something that will get out of your way and work well with little hassle, this is a very good choice.
That being said, Cinnamon is still in the middle of transitioning from Xorg to Wayland, so for the time being, some more advanced features like fluid trackpad gestures and multi-monitor variable refresh rate support aren't supported yet. (You can always just install one of the Wayland compatible desktops yourself.) Also, Mint tends to delay releasing packages for stability reasons, so if you need bleeding edge software, maybe try one of the other distros. (You probably don't need to worry about it, though.)
Nobara
https://nobaraproject.org
Based on Fedora
More Info ⮝
Nobara is a project that aims to take Fedora, one of the most popular general-use distros (see its entry below), and tweak it to be more friendly to new users by including tools to automatically install apps and utilities useful for content creation and gaming. Notably, it auto-installs the NVIDIA drivers for you rather than having to install them afterwards, and it includes WINE out of the box, as well as tools for installing various versions of Proton. Its desktop is simply KDE with a theme preinstalled and is the recommended desktop, though GNOME is also available if you want it.
Nobara is created and maintained by Glorious Eggroll, an employee of Red Hat, the primary contributor to Fedora itself. Glorious Eggroll has a good track record and has worked on numerous open source projects like WINE. That being said, he's still just one guy, and Nobara makes changes and patches to the system that could potentially result in bugs. I have never sat down and used Nobara myself, as it's a relatively new project as well. Though if you want the latest and greatest Linux has to offer and all out of the box while still being able to configure everything graphically, this is your best bet at the moment.
Pop!_OS
https://pop.system76.com
Based on Debian/Ubuntu
More Info ⮝
This is another derivative (or "fork") of Ubuntu. It ships with a highly customized version of the GNOME desktop focused on keyboard navigation and tiling windows, a popular desktop paradigm that's usually only seen in window managers. It also comes with its own set of GUI configuration tools and its own theme. I don't have experience using this one myself, but I know it's a highly recommended distro for beginners and features a very efficient workflow while still having the software catalog of Ubuntu.
Pop!_OS is developed by System76, a computer hardware vendor that sells systems with Pop!_OS pre-installed. Of course, they also offer the OS free of charge for anyone to use with no restrictions, but the OS is designed for and tested against their hardware primarily. If you want to, you can also easily install all the extensions that Pop!_OS uses to tweak GNOME on other distributions. It's also worth noting that due to internal disagreements with the GNOME developers, System76 is currently moving away from GNOME to its own DE called Cosmic that is still in early stages. The next major release of Pop!_OS is supposed to feature Cosmic included by default and is said to be coming later this year, so maybe hold on Pop!_OS until then. If you're curious about Cosmic's progress, you can view System76's blog here.
Good Intermediate/Advanced Distributions
The prior distributions are meant to be more or less plug and play with little user modification to use required, and there is absolutely nothing wrong with using a "beginner" distribution like Mint, even for advanced users. However, some may wish to have more control over what their system installs by default and not have a bunch of unwanted programs or utilities taking up space for no reason. For more seasoned users, many of the helpful graphical utilities installed by default on beginner distributions can be seen as unnecessary abstractions that get in the way of managing the system. The following distros focus less on providing a polished out of the box experience and more on giving users the tools to craft the system they want. More or less every popular desktop can be chosen during install, so you can get the exact experience you want. Some basic terminal experience is recommended. If you're good at reading and following instructions, it's not even a bad idea to try one of these distros out as your first one. It is my recommendation that Linux users that have become proficient at using the distros from the previous section give some of the ones in this section a try. You might actually like using them better.
These distros are what I consider to be the "big three" distros, as the vast majority of Linux users use either these exact distros or a distro that is forked (modified with custom changes, tweaks, and additions) from one of these distros, meaning that support will be very good. Of course, they are not the end-all be-all of good Linux distros, but these are the main ones I consider relevant.
Debian
https://www.debian.org
Independent
More Info ⮝
Debian is one of the oldest distros still in active use today, and has one of the largest selections of packages out of any Linux distro. Notably, it is the basis for Ubuntu, and by extension the basis for many other "plug-and-play" distros. The main "stable" version of Debian uses packages that have been tested to work well with each other and releases are supported for a long time, albeit with a long time between releases, making it a popular distro to use on servers. Note that in this context, "stable" does not mean "non-buggy" or "functional", it actually means closer to "unchanging software and bugs." Though in practice, Debian stable tends to have few bugs due to the testing packages go through. If you want more up-to-date packages and don't care too much about stability, Debian also provides "testing" and "unstable" branches to use. If you want a system that gets out of your way and lets you use your system autonomously while not caring too much about having new software versions immediately, Debian is a fantastic choice.
If you want a version of Debian that aims to be more user friendly while preserving the pure Debian experience, check out Spiral Linux.
Fedora
https://fedoraproject.org/workstation
Independent
More Info ⮝
Fedora is a very popular distro, with its distribution sponsored by the company Red Hat. It tends to be at the forefront of implementing new features before most other distributions. While Fedora is technically managed by an independent foundation, in practice most of the Fedora maintainers work at Red Hat, as Fedora is the basis for future versions of Red Hat's enterprise Linux distro. Fedora ships with the GNOME desktop by default. However, unlike other distros in this category, Fedora also offers numerous "spins," or seperate verisons of Fedora with other desktops preinstalled. If you want a crash course on various popular desktops, you can check out all the spins here. I consider Fedora to be a very "balanced" distro, with very up-to-date packages while still being pretty user friendly and easy to maintain. Just know that due to licensing issues, you will need to install various system components for media playback yourself.
Arch Linux
https://archlinux.org
Independent
More Info ⮝
Arch Linux and its derivatives are some of the most widely used distributions. Arch Linux tends to incorporate packages and updates very quickly after they are released, meaning the user can stay on the bleeding edge and get updates as fast as possible. This makes it a good choice for gamers, which is why Valve chose to derive the version of SteamOS used on the Steam Deck from Arch. Arch also has a package count that rivals Debian's in size. Arch is a rolling release distro, meaning that you never download new "versions" of Arch, the system just constantly receives updates over time. Arch also has what is known as the Arch User Repository, or AUR, where normal users can upload packages to be downloaded by other users. (Obviously, do NOT download random packages from random people without inspecting them first!) However, Arch's greatest strength, in my eyes, is the Arch Wiki, which is one of, if not, the single best sources of documentation for any distribution. Even if you don't end up using Arch or its derivatives, the Arch Wiki can still be a useful resource for troubleshooting other distros. Don't underestimate it!
In the past, Arch Linux had a reputation for having a difficult (to newbies) installation procedure. This is because in the past, there was no installer and the user would input commands at a terminal prompt to manually configure the system and install everything. In practice though, the vast majority of users simply copy pasted commands from the installation guide on the wiki. This led to Arch users gaining a reputation for thinking highly of themselves as Linux experts while not being that knowledgable about it and generally being annoying. However, modern versions of Arch come with a script called "archinstall" that presents a text-based installer that automatically configures things for you and lets you select a variety of desktops to choose from, so it isn't that much harder to install than Debian or Fedora. (You can still install it the old way if you prefer.) However, on occasion, updates may break system functionality. If anything happens that requires manual intervention, a notice will be posted on the Arch Linux website linked above. With Arch, if something goes wrong, you are expected to fix it yourself. However since the distro is so popular, chances are someone has had the same problem as you, so the solution is probably on the wiki. So if you're willing to read through the documentation and learn as you go along, Arch Linux is not actually a bad choice at all for a newbie. Just make sure you know what you're getting into.
If you want an Arch Linux experience that can be installed graphically, EndeavourOS is a good choice too, as it's basically just Arch with a GUI installer and different branding.
Tenative Recommendations
The following distros are ones that aren't bad, but have a sort of "gotcha" that might cause problems in the long term. Also they're just kind of controversial in the community right now. There's nothing stopping you from using these at all, just be aware of any potential pitfalls they might have.
Ubuntu
https://ubuntu.com/desktop
Based on Debian
More Info ⮝
Ubuntu is an interesting case. 5 years ago, I would have recommended Ubuntu alongside Mint as the best distros for new users without hesitation. Developed by the company Canonical, Ubuntu is by far the most well known Linux distro outside the tech sphere. Its mission was to get Debian's absolutely enormous package selection into the hands of the people, resulting in one of the first distros designed for the less tech savvy. And for many years, that was Ubuntu's main goal. However, over the years, Canonical gained a reputation for trying to use the influence of Ubuntu to force its own in-house technologies onto the wider Linux ecosystem. And recently, the most infamous example of this has manifested in the form of Snaps.
Snaps are basically Canonical's version of Flatpaks, packages that can run on any distro. However Snaps are pretty universally disliked for a few reasons. While Snaps can be installed on more or less any distro, they are designed to work with Ubuntu first before anything else. Applications running on Snap have noticeably longer startup times than apps running from traditional package managers or even Flatpak apps. Snaps have auto-update enabled by default. While Snaps are technically "open source" in the same way Flatpaks are, the only allowed repository for Snaps is controlled by Canonical, as opposed to Flatpaks where anyone can start a repository to host apps. If you want to use Flatpaks on Ubuntu, you must use the command line. Alarmingly, Canonical's Snap store has also been subject to fake apps uploaded by hackers that can steal user credentials. Even if the app you use isn't tainted, it still might not work correctly.
And to top it all off, commands to download packages from the package manager Debian/Ubuntu use, apt, are rerouted to download applications from the snap store instead if they are availible. Imagine on Windows if you went to download an application from its official webpage and ran the .exe file, only for it to then open the Windows Store and force you to install it from there instead because of Microsoft policy. That is essentially what Ubuntu does. If you want to remove this functionality, the process is in no way intuitive to new users.
Despite all of this, Ubuntu still maintains its position as an easy to install, easy to use distro for newbies. The vast majority of people won't really have any big problems with Snaps. In addition, many enterprise applications are designed to work on Ubuntu primarily. If you need to use an application that only supports Snaps, Ubuntu is probably your best option. In my opinion though, distros like Mint and Pop!_OS have surpassed it in ease-of-use, and they do not force Snaps on you.
Manjaro
https://ubuntu.com/desktop
Based on Arch
More Info ⮝
Manjaro is a derivative of Arch Linux that promises all the user choice and ease of updating of Arch while not breaking and being easier to use. It ships with utilities that make managing an Arch system easier, even doing things that are potentially destructive. Manjaro also delays package updates by two weeks so they can test them to make sure everything works. This is not an issue by itself. However, Manjaro also ships a utility (disabled by default, however can easily be enabled graphically) that lets users browse and download packages from the Arch User Repository. The problem is that if a user downloads an AUR package that requires a certain Arch package to work, but that package is on an older version on Manjaro, it can potentially lead to breakage. The GUI also doesn't really do a good job of communicating to the user the risks of using the AUR.
That being said, if you don't plan on using the AUR, Manjaro isn't a bad option. It's basically Arch but a little less unstable and with a more friendly installer and tools. If that sounds appealing to you and you understand the caveats, this could be a good distro for you. However, all of the tools Manjaro ships with can be installed on Arch and its other derivatives. If you really want a more friendly version of Arch, I'd suggest giving EndeavourOS a look as well.
I may not keep this in this category, as I haven't used Manjaro much.
Non Recommendations
These distributions are ones that I personally consider to be unfit for beginners alltogether. That does not mean that they are bad distros, but it does mean that they have either a specialized purpose besides normal desktop usage or they expect users to already be familiar with the ins and outs of Linux. If you want to go ahead and experiment with these distros, please do so. Just know what if you expect to daily drive these with no experience, you're gonna be in for a bad time.
Gentoo
https://www.gentoo.org
Independent
More Info ⮝
Gentoo is basically what people who know nothing about Linux think Linux is like. It is not actually a bad distro at all. In fact, if you are dead set on customizing your system right down to the most miniscule of system components, Gentoo is actually one of the best distributions to use. Its package manager, portage, does not offer binary packages like most package mangers but instead revolves around compiling packages from source. In layman terms, most package managers give you a pre-made application straight away, while Gentoo uses your machine's horsepower to turn the code into a package. Depending on how powerful your machine is and how complex the package is, this can potentially take a very long time. If you don't know what the term "compiler flag" means, this distro probably isn't for you.
In addition, its install procedure is infamous for being (relatively) complicated and arduous, to the point that "Install Gentoo" is a meme. (If you're curious about it, check out the Gentoo Handbook here.) It also requires more maintainance after installation than other distros. That being said, if you're a contrarian and want to install this as your first distro, go for it and prove me wrong. Good luck.
Kali Linux
https://www.kali.org
Based on Debian
More Info ⮝
Kali Linux is less of a normal distribution and more of a tool meant for people learning computer forensics and penetration testing. Essentially, it's a version of Debian with a bunch of pentesting and network monitoring software preinstalled. Kali Linux also leaves many security features disabled by default, as these features can make it more difficult to find security holes on other systems. Some people use it as their primary distro anyways because they think it makes them look like a pro Linux user or a hacker or something, when in reality it's no more difficult to install than normal Debian. While Kali can be a useful tool for those who need it, for normal users using Kali as your daily driver is not recommended. Just use Debian instead.