For newer Linux users or people looking to switch, it can be a minefield to try and find accurate and up to date info on what Linux distro to game with. Here to help. What is the best Linux distribution for gaming? It's actually not a tough question.
With how far Linux has come in only the last 2 years, you can play a seriously large amount of games now. Sadly, there's some (quite a lot actually) places out there that seem to slap a new date on old crusty articles and give really bad Linux gaming advice. Most of the people writing these types of articles elsewhere clearly don't use Linux - I do, and I have done for around 15 years now.
Let's start off with what not to do shall we? First off, don't bother with SteamOS from Valve. Currently, it's out of date and has been for some time now. It hasn't been properly updated since 2019! Valve are not working on it but they might return one day. Anyone suggesting it likely has no idea what they're talking about and any website listing it is junk.
Next: Ubuntu GamePack or any "specialized" Linux gaming distribution. You can throw almost all of those types in the trash. They really don't do anything normal Linux distributions don't do already and they can often introduce their own special bugs. I consider them like the old discs you would find in the bargain bin in a local PC store. You really don't need them, don't waste your precious time.
So what to actually install at the end of 2020 and in 2021 to game on Linux?
The answer is actually really simple, it's not a long list and you have two really easy choices: Ubuntu or Pop!_OS. With their LTS versions (Long Term Support), you can use them as a safe bet for years.
Why those? Well, Ubuntu is almost always the most widely used Linux distribution by normal desktop users. On Steam, it has always been on top as the most used distribution by gamers - there's an obvious reason for that too — it works. It's what I always recommend to newer users because it's like a warm cuddly Linux blanket. It's easy to find answers for, and it's not complicated to use. As for Pop!_OS, it's based on Ubuntu and since System76 sell desktop Linux hardware with it you can be sure it's also well tested.
If you do want a specialized distribution, perhaps for a console like experience that SteamOS was supposed to offer then take a look at ChimeraOS. It offers up a good big-screen experience for Steam.
Apart from that, everything you need can be easily installed directly on Ubuntu. Steam for the biggest library of Linux compatible games and for the Steam Play Proton compatibility layer for playing Windows games on Linux, Minigalaxy for GOG games, RetroArch for emulation, itch.io has their own client too for lots of indie gems and the Lutris game manager for everything else. It's really easy to get going too, on Ubuntu you just need to open up Ubuntu Software and search for Steam and it does it for you.
Don't make it complicated for yourself. I say all this as an Arch Linux user, which is a bit of a long-running joke about you always knowing who an Arch user is as they will tell you - and oops, I just fell into it. I'm saying it for good reason though! I have been through Arch Linux, Manjaro, Fedora and more and I still consider Ubuntu to be the number 1 Linux distribution for getting going quickly especially if you're not too comfortable yet.
Keep in mind that just as macOS and Windows do have plenty of issues, so does Linux. Don't expect perfection, be prepared to learn a bit and do things differently. If you need help, we have plenty of resources available for you. We have: a Forum, a Discord, IRC, Matrix, Telegram. You will find answers across there, with the Forum being the best way because search engines pick up answers from forums and do not from social chats like Discord.
Lastly - have fun and keep on gaming on Linux.