Magic damage, hit, and break are the most important mage stats for damage.

Dodge, Skill Defense (Cianna and Adamanti defense, really), and Health are the most important damage reduction stats for mages.

Everything else is a nice-to-have, but not imperative.

Note that this primarily applies to PvP. Heroic Realm/Questing encounters require all sorts of odd setups you wouldn't ever use against players.