So far, I've got to go with Fable 2 and Force Unleashed.
Fable 2 not only looks amazing but it's a lot of fun the whole time. I never hit a deadspot playing it. Granted it's a bit short, but an amazing game nonetheless.
Force Unleashed, I don't know where to start, visually stunning with one of the better Star Wars stories told. I have a lot of fun with this game.
I still have to get to Fallout 3 and CoD5, I haven't played enough of Fallout 3 to judge, but from the little I've played, the game is amazing on every front.