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.
It was hard for me to experience the better gameplay you're talking about because the controller gimmick was mandatory and very unfun for me to play with. I wasn't particularly fond of other games using that second screen as a mandatory inclusion, either. Also, because it's a story rehash, it felt more like a pretty but clumsy SF64 remaster than a new game.
The opening cinematic was amazing and should have been its own movie/show, though.
I mean it's all subjective but I personally liked the controls and I'm sad about how hard they were rejected by the masses I do dream of a Switch port that makes them optional though, because I feel like the game itself deserves a second shot. There's a lot to like in the campaign (except for that helicopter level).
I don't want to yuck your yum there, so I'll just share frustration that Star Fox is probably mothballed indefinitely now.