I guess MW2? I dunno. (So far, it's the only CoD i've played. I've never played online, though. It was at my friend's house where I played MW2 in multiplayer. He's too hard to beat.((Yes, he beat me a couple of times. I didn't win even once. He even did a Tactical Nuke.)) I've heard that MW2 doesn't have dedicaded servers but BO does, just so everyone knows.) I've never played BO nor I have it so... yeah.