I've only consistently played one Battlefield game, it had a decent community.
DOOM's community from the Skulltag Online days was always awesome.
I think Quake's community is split between games, you have the QuakeWorld elitists who hate Quake III and vice versa. Same goes for Unreal Tournament.
TF2's community probably got worse after F2P, I've seen complaints about teams of only Snipers with no Engineers, where all of the Snipers suck and there's no communication.
CoD's "community" is so widespread that you'll have a handful of decent people but the majority of them are braindead forgetwits.
CS had a better community than I expected when I started playing.