My favorite 3 Call of Duty is WaW, then MW2, then Black Ops 1!
I think Ghost will be more popular, to be honest. But it can barely be anything but a close match.
Each game is different in their own ways.
Call of Duty is the same as battlefield, if you think about it, they're both the same in every release, each has almost the same playlist, almost the same expectations, and someone better graphics all for 60 more dollars from release until the 3rd year.