Halo: Reach
Brink
Portal 2
Can't really choose between those three, but they sort of cover everything I want. Reach for that familiar game that pretty much everyone I know will have. I've found that Halo is sort of that main game that everybody can find something they like in. I like games that my friends don't like, and the same with them, but we can always agree on Halo. Brink offers something new and innovative to multiplayer, and has the customization and teamwork that I've been craving. And Portal 2 is that great, innovative single player FPS I've been craving.
Oh and I almost forgot: Fallout New Vegas. Although I wasn't too big of a fan of Fallout 3 and never finished it, I'm planning on giving New Vegas a try with the realism mode, because it looks like it's going to bring the kind of survival gameplay that was missing from Fallout 3. In Fallout 3, once you leveled up enough, got nice enough equipment, and could carried hundreds of stimpacks with you, the gameplay got a bit dull for me. Sure, exploring the wasteland and meeting the characters is fun, but it's a fucking post-apocalyptic wasteland, and I want to struggle to survive.