Argonian, since it's power would make it pretty much invincible for a minute and it wouldnt take that long to destroy everyone else. --- SNES FAQ Completion Project http://www.gamefaqs.com/boards/2000094-faq-contributors-general/60384415
Mostly because of the Sparks, Flames and the Healing spell (which nearly every race gets). It'll be extremely hard for most melee warriors to get close, and even if they do, they'll instantly get killed with Ancestor's Wrath.
If any other mage race tries to kill the Dunmer, it will be meaningless since the Dunmer only starts with Sparks and the Flames spell which most mages get, won't be effective against the Resist Fire power.