For me "best game on Linux" basically just means "best game" since everything I play runs perfect of very close to perfect.

That means Terraria is the winner for me. Best game of all time IMO, and it has a native Linux port that works great.

Most games run in Linux these days. It's especially easy if you have your game in steam and enable proton in settings. As for a favourite. That's hard to say. I have accumulated so many games over the years, I can't name a favourite. I played a lot of overwatch before they messed it up with the f2p patch. Otherwise, I've been playing some rimworld lately and some don't starve together. Edit: It just struck me. Underrail is a game I could count to my all time favorites.

FTL has held up surprisingly well