Try 2 or three specs and decide for yourself. It's really going to depend on your play style.

I've done fire-frost, then switch to dual pom pyro. ( very fun )
After seeing how OP Arcane could be after the patch, I switched to dual Arcane. It was ok, but still leaves you very squishy. It also leads to lots of problems with your toons breaking follow.
Now I'm dual frost, and I must say it's really fun. I'm not nearly as squishy. Having 2 elementals out and giving you back mana is pretty nice, and I have lots of ways to avoid getting hit.

Really, re-speccing isn't expensive. So, try something that looks interesting to you. If your not really feeling it, try something completely different. There are a lot of fun mage specs, but it just depends on how you like to play.