This thread is simple, which spec do you find the most overall fun, whether for PvE or PvP (specify which by the way, as I myself am only involved in PvE currently since I'm leveling).
I was Frost up until around 70 where I tried out Fire. That became kind of grueling. Last night I was so bored on my Fire mage I finally decided to give Arcane a try, and I think I like it way more. I don't see how anyone can be thrilled by playing a Fire mage.
I think I enjoy Arcane/Frost more simply because there is more to do than just hitting two or three buttons in every situation.