I've played on both sides on EU and I can honestly say that the Alliance, well at least in my experience, are more communicative than Horde. When I talk in BG chat I tend to get some kind of response, heck I even see people rage. While on the Horde side I have never really heard someone talk/rage. And if they did rage it was at the end of the BG while they didn't communicate AT ALL.
I prefer to see people rage in BG chat because that way you know there's a bigger chance they will co-operate with you, and they also come up with plans themselves.
Also I noticed Alliance BG queue is shorter than Horde BG queue.