As much as I dislike WoW after 3.2, I still have to say it was pretty epic before that and deserves a mention.
Dragon age: Origins (hated the telepathic protagonist though:P For some reason it gave off a really bad vibe.)
Runescape
And from older games
Sacrifice deserves a mention. It was the first game I played more than a few hours.
Black and White and B&W 2
Sims (havent played the newer ones though)