Without more information on your intentions (MF, PvM, PvP, Rushing) and the rest of your build (single tree, dual tree, tri tree) it's hard to give the right advice. As a guideline, I agree with WTG, if you are going dual-tree I would recommend FO with FBall/Meteor (Meteorb build). If you are going single tree, use Bliz (max Bliz/Mastery/Glacial/Blast/Bolt in that order).
________________
Darzog