I would also vote ranger. Why? It's so easy to level. With a tank pet you are unkillable to anything but champions. And then when you reach 80 you can get Druid, which is a superb healer, giving you another aspect to use, and then Soulbeast, which is a great elite spec. Ranger, Druid and Soulbeast -- it's about the best group in the game. Each one is viable and allows you to do different things.