If your going for racial benifits, gnome has the best racial trait. In the very end game, a gnome will do more damage then any other race due to +5% to haste effects... So for a 40% haste item, you would get 42% haste out of it.
That being said, stats play a much more important role in SoD, and a barbarian has the best starting stats. Dwarves also get great starting stats. With illusion masks and perma illusions, id say pick the best race and use illisions to look your prefered race.