Well i played COD4 on a buddies console, but at the time i was a Halo guy all the way. When WaW came out it compleatly changed how i view COD. It drew me in and is still my favorite game. Take tha hackers away, add in host migration and i would play it over any other COD.
However the last campign to draw me in comleatly was BO1 . I still enjoyed the WaW and even COD:BRO (which i played campign only) more than black ops. While the COD4 and MW2 campign was decenent, it jsut didnt do it for me (i really think the history of games set in the past makes it better) However these last couple of games (MW3 and BO2) i was less than impressed with the story line, and only played it one time through, without bothering to beat it on veteren like the past games