Human is the way to go.
I just leveled my Bloodelf priest to 80 to play with my friends that faction changed. I have a Human priest on the same server as well. Best of both worlds!! The only small problem is that I keep mashing the hotkey for arcane torrent on my human priest now and it's not there
“We all have great inner power. The power is self-faith. There's really an attitude to winning. You have to see yourself winning before you win. And you have to be hungry. You have to want to conquer.” ~Arnold Schwarzeneggar.