Halo 3 blows everything away, because I’m such a massive Halo fanatic. (Seriously, I own all the novels, the ‘Art of’ book, an unofficial book about the look at the success of Halo, all the soundtracks, and more.)
After that, I’m looking forward to Hellgate: London, Halo 2 Vista, Forza 2, Mass Effect, Smash Bros., and a few other things—mostly 360 stuff.