Let's see in the past:

Astonia 3
Dransik (before it turned into Ashen Empires)
Mu Online
Lineage 2
WoW
Rift


Just quit Rift, lately I think it's just a waste of time, and same goes with a lot of MMOS. If Diablo 2 counts, then I'd say that's the best one so far. Even though I don't play anymore.