COD3. I stopped beating the campaign after MW2, but I got kid close in BO1. I hated MW3, but this game is pretty good for me so far just in MP. I'll be trying the single player out more than likely as the game looks interesting. Plus, y'know, future tech stuff.
Get it right, do it nice. If you make a mistake, you're gonna pay for it twice. If you need it... got to have it. Get yourself a shotgun and bring it back home