BR's some of them can play together, even thought they're not known for being good players they always try their best, the community itself is known for not playing that good and QQing a lot.
Latinos, I think they might be the worst, they play by themselves most of the time and flame you either you kill them or get killed by them.
Greeks & Russians, not much to say about them, they always invade all the servers and try to zerg everything, team play? Well... Not much that I've seen until now, at least in official.
Polish, they're really concentrated in the game and know a lot of stuff about it, I've meet some funny polish people in my time.
We, Portuguese people, I've been in portuguese guilds since I can remember and we would always have organized CP's. We aren't the kind of people that QQ because we can accept our weaknesses and improvise later on.