I am a Frost Mage and i like it because i can just freez the target and back up to do more dmg also i can just send my elemental after them "get at lvl 50 for frost mages" and im fine + a water elemental is just sweet while fighting on bosses and stuff because you can just use there frost nova if yours is on cooldown.

The Fire mage is also cool with all the dmg that they do but they cant realy kill the large mobs of Non-Elites unless you have ALOT of health while a frost mage has Ice Barrier to protect them with there Water Elemental and there slowing spells. but if you like to PVE then fire mage is a pretty good choice

The Arcane Mage is also good in PVE altho i donot know mutch about them infact i hardly ever see a Arcane mage around but im a Instance persion.

Arcane/Fire mages have frost nova too.  And Frostbolt (rank 1) for kiting.  And ice lance for easy 1-2K damage after frost nova.  And cone of cold.  And blizzard (rank 1) for finding stealthers in bg's.  And NOW, Ice block.  And, well, you get the point. 

All this, plus improved counterspell, extra intellect, Spell Power, clearcasting, Arcane Power (extra crit dmg), improved scorch, ignite, 70% chance to resist pushback on fire spells, mana regen while casting (lol, almost never run out of mana if only use scorch), Blastwave, and of course, Presence of Mind and Pyroblast (although that's really pretty insignificant in the overall picture). 

Not to mention an additional 10% chance to crit with scorch (4+6), 3% more crit chance from Arcane Instability, and an additional 3% chance to crit with all spells due to clearcasting (10% * 30%).

If you know how to use ALL of your spells, you will own in PvP, no matter what spec, but as you can probably guess, I have a great time with arcane/fire (33/28, scorch spec), but only when I use the frost spells properly.