For me it's Diablo II. Granted I've played my fair share of D2 since launch, and also recently on a private server with a comrade from hexbear, but I still feel like years later the game didn't grab me as much as D1 did.
Granted I don't hate D2, but for a game that I keep coming back to, D1 takes the prize.
I will always hate the treat defender take that "well this doesn't bother me and I don't have a problem with it so it shouldn't affect anyone else unless they're weak-willed" or some passive-aggressive lowkey calipers like that.
Hexbear was infested with that during the struggle session against international corporate sports gambling apps.