for me, it would be...
Storm Calling
Dark Magic
Restoring Light
The storm calling tree is able to fill all 5 weapon slots for crazy AOE dps, Dark Magic has wonderful CC and single target DPS as well as Dark Exchange, which is wonderful for mages, with Restoring light as the third, this build would be the best in AOE DPS and great single target as well, Powerful healing capability with the highest possible magic sustainability.
that would be one of my 4 characters, my dedicated Universal Mage
I play every class in every situation. I love them all.