Prototype was this year?
Crumbs! It feels like forever and a half ago!
For me it's a toss-up between Plants Vs Zombies and Dragon Age and ultimately I think the only thing that separates them is longevity. PVZ is a wonderful game and I played it solidly for days with a big, stupid grin on my face but Dragon Age had me for the best part of a month; to the extent that it threatened to become a lifestyle. I still want more too!
The gents at Bioware have my vote, and my first born if they so wish.