Scribblenauts. By far, pretty much.
Runners-up, in no particular order:
The Saboteur, Dragon Age, Muramasa: The Demon Blade (played the Japanese version quite a bit; a-mazing), The Beatles: Rock Band, DJ Hero (I'm a IIDX elitest, but I'll give it a try), Rabbids Go Home, Borderlands, Avatar, Left 4 Dead 2, A Boy and His Blob, Batman: Arkham Asylum, Half-Minute Hero.