I am going to have to go with COD 4. In all honesty, Call of Duty will never be what it used to be. It's just way to complex now.
This is just my opinion though..
Call of Duty Modern Warfare 2 is and always be my favorite Call of Duty Game, mostly because of the trickshotting. Although Call of Duty Black Ops was pretty good too.
Obviously not Ghosts.
I prefer Black ops 1 / 2
Great games in my opinion. Ghosts lived up to it's hype for a day, the lobbies came out and killed the game instantly.
To be honest I hate cod. im a halo kid, but Id have to say MW3 wasnthe best, or cod 4 if it wasnt mod central. Thats another reason halo shits on cod... look at cod 4 and then look at h3.. Mods EVERY GAME in cod, in halo you MIGHT get matched up with a jtagger but its rare asf. What about you?