Originally Posted by
Neoxx
Fire is by far the best spec for leveling IMO, espacially overgeared. You almost have no downtime, mostly instant casts, low CDs, great burst, great AE dmg, you survive group pulls, Dragon's Breath stun, blink selfheal if you choose the talent. Also with the archimonde trinket you have perma slow and free AE dmg 24/7.
Arcane suffers from long cast times when Charge Up and Orb is on cooldown and the mob is not dead. Group pulls are a pain since AE and Resonance got nerfed so you take too much dmg. Also no self heal, no stun.
I tried frost, but it was meh as far as I remember. Can't say too much about it, fire was just better so I switched back.
Dispite of all that, you kinda have to level as the spec you will play in raids/dungeons later. So it's most likely a choice between fire, fire, fire and maybe arcane.