One thing with high population is you get a lot of lag. I play on 5 different servers and Bria has the most lag by far. Some other good servers with good population are Bloodfin and Intrepid. There were always people around and they didn't lag as bad as Bria.
But if you check out the thread at the top of the forums you will see that Allakhazam users have formed a guild on Bria so you might want to get in on that.