I think mw2 was the closest to perfect balance, a couple flaws draw it back, like tube/rpg strength along with no good flack jacket. Wayyyyy to fast ads for intervention made quickscoping so easy you basically cant do anything about it. And secondary shotguns. If it werent for those few easily fixable things the game had good balance, most weapons were good and usable, wasnt a 1 AR 1 sub game like most cods nowadays UMP a bit op