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.
Diablo1 had more of the rogue like roots. Diablo2 was more overtly cartoony and loot-grindy. It became no longer a question of “can you clear the game?” but “can you clear bosses quickly for good loot?”. Diablo3 went even farther in this direction. I didn’t play 4.
Pretty much nails what I came to get burnt out on in 2.