Personally I use Sway. I wouldn't recommend GNOME. KDE seems okay from what I've used of it on SteamOS, and I have a few friends who seem to like KDE as well.

For a distro, maybe Arch or Fedora. Be aware with Fedora that it's more work than most distros to get proper media playback of certain codecs working, due to some sort of fear of patents. You have to replace a bunch of packages and it took me a while of messing around when I set up Fedora on an HTPC before I got the expected performance with various videos. I run Guix System on my personal machine, but it's pretty advanced and niche, so probably wouldn't recommend it to a new user.