I personally had no issues lvling my warrior tank to 80 in a short amount of time (for my first and only lvl 80 toon and still my main). I found it easy to solo, and always useful in instances. Now learning the higher lvl tanking duties, but still enjoy it a lot. As for druids, I don't disagree, and recently converted my lower lvl Druid to a healer spec to avoid another tank in the arsenal.
Paladins and DK (can't start at lvl 1, obviously) tanks are both great, as they have self healing, but if your tanking, you shouldn't have to worry about healing yourself in instances... but useful if soloing while leveling.
I say, Warrior... don't do Horde, but if I did, probably Tauren.