Ele shaman I think is a little better than all the casters. Sp can kill me sometimes, rest I usually win. But fire mage and boomie are a blast as I have both, and a destro lock which is also fun. All are viable, just pick one that suits your style.
Here is my fire mage in action >
Having a shield gives you 48% armor. Plus the 10k shield you get from the Stoneclaw totem every 21 seconds is huge too. Root every 10.5 seconds with the earthbind totem, shock every 3 seconds, and 7k lava bursts every 8 seconds. My toon sits at 606 resilience too with 1423 sp. It allows me to deal with melee no problem, and 1v2/3s pretty well.It's between an ele and a shadow priest at the moment, but they all look fun.