Ubuntu or it's derivatives. With a careful use of PPAs you can have a very good and capable system. Canonical has been doing some stupid stuff lately, but no big deal. Since you are using nvidia, I would avoid rolling release distros like Arch since those can be a nightmare with proprietary binary modules.
Steam will work no problems and most games can be made to work with Proton. Other launchers you can easily get them to work with Lutris. Anti-cheat will be your biggest problem without resorting to some complex hacks, but there is some work being done in that area from Valve and Epic.
I largely agree, although to be fair, I've had less trouble with nVIDIA drivers running Arch than with Ubuntu derivatives - they're well behaved until you have a big update (like moving from 18.04 to 20.04, or 20.04 to 20.10, or Mint 20 to 20.1) then things tend to go to hell in a handbasket. I run a couple of Arch systems at work and they're always well behaved. The only times I've had major issues with Arch is when I've not updated it for a very long time (I'm talking 9+ months here, because I stuffed a laptop in a cupboard and ignored it for nearly a year).
But the potential for things to go wrong with a rolling release distro are higher than one with a more stable base. Given that the Steam Deck will apparently use Arch, Valve must be fairly confident they can make it more approachable for non-technical users...
Easy Anti Cheat and BattlEye have announced Linux support coming.
This will probably start a fight, but who are these people who want to game in Linux and why? I've personally fooled with Linux going back to the old 3.5" floppy "Red Hat" days and was never impressed. I even went as far as to install Mint on my big gamer and ran some games under Wine. After I did all of that I wondered to myself why in the H--- I even bothered, as performance was atrocious. And here's where the fight starts: Linux is hard to use. I'll bet a nickel to a hole in a doughnut that the average user keeps a "cheat sheet" near by just to get their word processor up and running. But, Linux users take heart, as Microsoft is here to the rescue. No more Debian woes as the boys in Redmond have your backside now. (LOL) and more (LOL).
You're either trolling, biased for reasons undertermined or haven't used Linux since Red Hat Linux became Red Hat Enterprise Linux. Thanks for the laugh, though.