We might not like it in the slightest, but Jaina apparently transferred from being OP to being a God due to Thunder King shenanigans, even Thalyssra is afraid of her.
My question is, do we have someone with the same level of power in the Horde? Thrall doesn't seem to be the OP shaman that he was, and I don't think Sylvie can solo an army.
Safest bet might be Ebyssian, not sure.