One of the few races I would play as new allied race would be Vrykul. I believe that they fit more in the Alliance than in the Horde, due to the Human vs Orc theme. After all Vrykul are to Humans as Trolls are to Elves, right? And they look too "Human" to fit the horde theme
Here are the classes i feel that fit in their lore:
- Warrior (Warrior Class Hall says hello)
- Paladin and Priest (Val'kyr, Eyir, battlemaidens)
- Death Knight (relevant race from Wrath of the Lich King)
- Hunter (for example the hunter class mount quest)
- Monk (brewmasters)
- Mage (there are vrykul that know magic)
Missing a warrior in the alliance, so a Vrykul is a nice candidate
What do you think?
Also, as a Horde counterpart, ogres could be introduced as well. (big guy for a big guy, right?)