Diablo 3
The amazing thing is that no matter how much I've played Diablo 3 on the PC (and it was a lot, believe me), it was just tremendously entertaining on the Xbox 360, even though I knew what to expect around every corner. Same enemies, same environment, same bloody story.
Smooth and almost flawless gameplay that's still hellishly addictive (almost diabolically; in fact); a game you'll enjoy from start to finish and you'll probably start playing it again once you're done; plenty of class-specific loot awaits this time around
It's been a long time since the PC version and still no fresh content, they could've at least put a new class in; interface issues in local co-op