MW1 and MW2 are my 2 favorite CoD games and I've put in almost 20 days combined gameplay. So I will definitely be buying MW3. Besides Halo, no other series provides as much diversity in game modes and gameplay as CoD.
As for BF3, I can't say that I am that interested yet. All of the trailers are for PC and I don't have computer that can play most PC games. As of now, I'm not that excited for a gimped console version. I really need to know how BF3 will be different from Bad Company 2 on PS3/Xbox. Bad Company 2 was a pretty dull game for me-- slow-paced action, bad progression system, too much delay before entering combat, poor hit detection, and terrible variety of game modes. How wil BF3 improve upon Bad Company 2 for consoles? So nothing for me to be excited about yet.... hopefully E3 gives more info.
Most anticipated games of 2011:
Uncharted 3,Legend of Zelda: Skyward Sword, Rocksmith
Modern Warfare 3, Super Mario 3D
