Diablo III. Hands down.
I broke my hand when this game came out, and I should have took that as a warning to stay away. But as a die hard Diablo I / II, I played anyway. The Real Money Auction House (and probably the Auction House in general) completely ruined this game. They are doing a lot right now to fix it though (Even removing the AH completed), so we will see how it turns out. It's really a shame what they did to it though, they had the perfect formula but ruined it.
Better luck next time, Blizzard!