Diablo II for sure for me. This game i've spent soooo much time playing. The music, the atmosphere, the gameplay, the story, the loot system being literally PERFECT. You played a lot and then one day you just kept finding new secrets like the Uber part. It shaped the way H&S would be made later on. D3 was such a cash grab and had no soul that even with the updates and expansions i hate that game with a passion. Still haven't played DII ressurected but i def will and D4 is also looking like a step in the right direction after II.
I would say Majora is runner up and Paper Mario third.