COD1 and COD2 were just epic because of the rifles, COD4 brought it to a new level which catched me the most. WaW was great too because of the coming back of old weapons. MW2 had a whole other mulitplayer experience, weapons are lesser balanced for me. Black ops 1, brought for me again that cod4 feeling back somehow and MW3 feels like a more balanced MW2. didnt bought Black ops 2 because of the futuristic shit (IMO).
I hope the new one is going to feel like COD4 or Black ops 1 again....