I'm a bit sketchy on the names (its been a while since I played the xbox) In the order I remember playing them: MW WaW MW2 BO Forgetting the story line on the campaign mode (they're all boring as shit to me) and focusing just on the PvP, I would have liked MW the most, but for the match making system (I'm based outside of the US and the system did not have a local search feature). The game was very unforgiving on a 300-400ms ping off host. I remember liking WaW and MW2 the most because of the local search feature. I can't remember much about BO.