Rewind to a few months ago, and I would have answered this question for you in an instant: 
"Split/Second! It's made by Black Rock and therefore is the winner!" or something to that effect.
 
However, as we draw close to release, the line has been a little blurred. Pun not intended.
 
Blur came out fighting with a multiplayer beta than frankly, rocks. It's wicked fun to fly into someone on a corner, unleash a barge and then boost away. 20 player online is also quite an achievement and I think it's managed to create a frantic experience that Split/Second simply wont be able to match unless the explosions happen every couple of seconds. This remains to be seen, but I do believe Blur might have stolen Split/Seconds thunder by being amazing.
 
It may truly be the Mario Kart for grown ups that some of us have always wanted.. And that many more of us never knew we wanted but now we've played it can't think of living without it., Looking forward to seeing how it turns out!

Mostly I want Puzzle Quest: Galactrix.

Brutal Legend will probably be amazing just because Shafer is making it, and Chronicles of Riddick: Assault on Dark Athena will also be a good one I reckon.

Sounds like Heavy Rain is going to be Fahrenheit without the hamfisted bits that held it back from being a truly amazing game, so I have pretty high hopes for that too.