Borderlands 2, best co-op game I've played since Serious Sam..
Not a big fan of BF3 or MW3, I'd pick Crysis 2 over both. Haven't played Homefront or Deus Ex (I've planned on checking out deus though). Portal isn't really a fps game. CS GO was a lot better than source, but I still haven't been able to play it as much as I'd like because of our terrible internet connection.
Yeah, I agree. It's not an amazing game by any means, but it kept me entertained and it didn't feel like I was playing the same game over again.