Mw2. Imo opinion, maybe bc it was the first cod i ever played but i just feel it had good maps, killstreaks, weapons, imo overall i thought it had a great balance all around. Cheating/ modding/ lag felt pretty minimal and iw stayed on top of its game pretty well. Its too bad iw has fallen apart they made a great game. Now however its almost impossible to find a legit lobby anymore. I also think all maps should carry over to the next cod for instance mw-mw2-mw3 or at least one extra every pack release like terminal. Id love to see rust come back!!!