The Vampire Lord is hands down the best option for a mage. Note that to become a Vampire Lord, you must have Dawnguard DLC installed. Transforming into a Vampire Lord will be able to unlock powerful perks to aid your magical spells and skills. Straight out of the bat, you get 50 bonus points for health, Stamina, and Magicka; all the better, too, because you'll need the extra Magicka to cast Blood Magic, a new type of magic limited to Vampire Lords. As a Vampire Lord, you can summon Gargoyle and raise the dead to fight for you.