ehhh i cant agree with that.
imo cod4 was the best, it just didnt get boring. the single player and multiplayer was amazing and no one truly expected it for the most part.
then waw came out and the campaign was baller! but i just seemed to get bored of the maps faster and not have as much frun
mw2 i believe is better than waw and more exciting and a great overall game but cod4 still has my vote for best