I'd recommend either a Lock or another Shaman. I currently run Pally/Priest/Hunter/2x Shaman and the additional Shaman is invaluable for the second set of totems. Plus, Shamans can gear up pretty quickly to 3K+ with a couple weeks of heroic runs plus some selective AH upgrades. A Hunter isn't bad for pure dps, either, but they can be a liability as a new 80, plus they don't offer as much utility.