Diablo2
Replayability of the game is insane. Multiplayer was great before hacking but that wasn't a problem until the game was well passed its prime.
Lunar and Lunar 2
Two great stories. Not only are the games good, they also came packaged with toys and collectables
Castlevania(s)
All the 2d versons of the game are great. The 3d versions weren't great but Gameboy advance is keeping the series alive.
Honorable mentions:
Zelda
Metroid
Final Fantasy 6/7/9/tactics
Resident Evils
Silent Hills
Other great games that just aren't coming to mind right now.