If we start taking some pieces of the occult into this (demons, ghosts, etc.) then we may as well take all into it. Humans, in that case, if knowledgeable enough in the subject could be much more powerful than any of the listed possibilities. Dealing with Stormcloud's post that also would include liches, being that generally they are some transgression into a powerful zombie (with most examples of zombies I'd say they were closer to humans, they actually have some semblance of understanding other than "HE HAS BODY HEAT! MUST KILL!"), and there wouldn't really be a point to taking the other, flawed, choices.