I went fire. Fire starter and Meteor would be the only 2 talents I would suggest, rest would be up to you.
RoP is great for leveling, because its 'downtime' is when you are going to a new quest or group of mobs and RoP + Combust is still a great burst for blowing up a harder mob quickly or pulling large packs and killing them all very quickly. You could do it without RoP, I liked it though.
I did have a bit of a play with frost leveling, I just found the blink heal to be worth more to me then the big frost shield while leveling.
I've leveled 3 mages now, thanks to my desire to play all 3 specs with their best legendaries and blizzards shitty design.
You're gonna have the easiest time if you go with fire. The talents are totally up to you, whatever you think is fun. Kindling is pretty great. MI and RoP both have merits. Living Bomb is incredible for AoE. Meteor will let you 1 shot something every 45 seconds.
But the real reason is that frost and arcane cannot really compete with the sustain that getting Cauterizing Blink right out the gate will grant you. I know its a defensive and it feels dirty to recommend charging for that first over damage, but damn that APtrait is incredible. I'm hoping the 7.2 two-trait relics are an offensive and defensive one strictly, 100%of the time, so I can get more cauterizing blink without losing damage.