What I think the best the mage is a mix of all three.

Frist Arcane talents to lvl 50.
Do as such:
Arcane Focus, Magic Absorption, Arcane Concentration, Arcane Fortitude, Arcane Meditation, Improved Mana Shield, Improved Blink, Arcane Mind, Prismatic Cloak, Arcane Potency, Spell Power, Empowered Arcane Missiles, Mind Mastery, Slow.

Then ether Fire or Frost to lvl 60.
As such:
For Frost: Elemental Precision, Frost Warding, Frostbite, Improved Frost Nova.
For Fire: Impact, Flame Throwing, Improved Fire Blast.

And then the other to lvl 70. And once lvl 80 comes out, you'll have 10 more talent points to spend.