Counter Strike or BF2.
Maybe COD2 or UO, but not WaW or COD4, those are just spray spray spray with all the extremely low recoil guns like the RPD or the no recoil 'I win gun' the M16, get killed by random frag, spawn, spam three frags or grenade launcher over the map, get a kill streak, camp so you can get a helicopter, get killed by martydom, or someone with Juggernaut, helicopter goes and gets loads of cheap kills for you, repeat process. The whole game is based on cheap kills and made for the ADD masses, hence why it's full of kids.
I can't belive COD is beating counterstrike. Just goes to show who's being playing online games for a while and who started playing with the 360/ps3.