Mage – What Professions are Best for PVE?
Tailoring + Engineering are going to dominate most of the expansion.
Tailoring: Spellfire, Frozen Shadoweave, Spellstrike Set Bonus, Boots of Blasting, Mantle of Nimble Thought, Sunfire Robe
Engineering: Flame Turret, Sappers, Teleporters, Goggles, Mote Extraction, Rocket Boots
For a time you may consider dropping tailoring as you transition out of Spellfire/Boots of Blasting, but you would most likely want Tailoring back for Sunfire Robe.
If you choose to drop Tailoring/Engineering other options include:
Jewelcrafting: BoP Gems and JC Only Necklace (Phase 5)
Enchanting: Personal Ring Enchants (12 SP per ring)