NixOS is pretty nice imo.

It's pretty stable, has a good package manager, and is quite declarative thanks to the Nix language based config. It also supports Steam and has a dedicated "Games" page in the wiki (https://nixos.wiki/wiki/Games).

Downside is it's unlike pretty much every other distro, and could have a steep learning curve.

Been using it about a year without problems, would recommend.