Not OP, but proton isn't Linux it's the software that makes games work on Linux, largely you don't need to mess with the version of it (unless you're into tinkering or something is behaving weirdly) as for which distro, that's kind of a spiritual journey lol, find the one that clicks beat with you. I prefer Arch, but have heard good things about PopOS, Mint, and CachyOS. Of those CachyOS is the one that was specifically built to game, but ultimately the difference between distros of Linux is (for an average person) basically just what package manager you use.