A lot of classes provide great utility, and imo grounding totem isnt really worth much anymore in heroics. I run a pally+mage+3 shamans, and frankly I might replace one of the ele shamans if patch 3.08 doesn't up their DPS a bit. my mage, in basically equivalent gear, does 20-50% more dmg than my shamans. Now that I've spec'd one resto I rarely need to use all the shamans to heal as well. And of course free food + teleports + int buff is great, and if you spec frost you do +10% caster dmg buff plus replenishment when water elemental is up. The downside is that on hard bosses my mage dies. A lot! A complete lack of a heal button can be a big issue sometimes.

I thought about a hunter, but my concern would be that in the hard instances the pet wouldn't live long. Other option is boomkin for extra crit and 10% dmg buff, plus their ability to heal in a clutch is great.