If you keep the mage in the group id go arcane, it would be easier. Ice is nice for the control but it takes alot of hands on with targeting rings (blizzard and pet) to get the most out of it. Also, you are already going to have plenty of pet commands to issue, why add another..

Fire is nice as well, at least down to pyroblast.

Arcane: you get the AOE that doesn't need anything other than a button smash (no targeting ring to deal with).. Arcane missiles aren't the most effecient spells, but since its channeled it will rotate the mage towards the target.

Another reason to keep the mage around is the ports.