I think Bazzite is the “easiest”. But I think it would be very difficult to tinker for someone not used to Linux. It’s the plug and play option. For me the fact that bazzite tries to be immutable is a very good plus for stability on the long run. And somehow fits well for gaming on Linux. The drawback is that these immutable distro are hard to tinker with if you dont have experience with immutable package managers and so on.

CachyOS has maybe a more traditional structure but should offer good performance too.

There is also Nobara and Pop OS.

I’m on PoPOS but it’s too recent for me to give feedback for gaming. But it should work well too.

I suppose to some extent that it depends on how aggressive you clean up after system updates.

It seems like on both Silverblue and NixOS there is stuff you can do to prune and cleanup unnecessary stuff.