Definitely Fable 2!! I love the Fable series, and my only complaint is that--once again--the game is a bit short. I love the references to the last game, and the item descriptions are hysterical!

But I love Oblivion, too, even though I haven't got the attention span to finish it.

An X-Box (not 360!) game which I LOVED and which I think didn't get much advertizing is Bard. That game is SO FUNNY, but not for kids, I think. *grin* I bought it used for like $5. Well worth it!