Not an option really for magically weak Man. In most cases PoD will be better than wyrm but though the times when I thought that astral wyrms are uber have passed, if I decided to take wyrm as my pretender I would think of adding some magic. In most cases earth is the best option because you get reinvigoration which guarantees that he will not be swarmed and when you later add four other artifacts your wyrm will remain a force and probably won't gather many wounds. I don't think that a pretender should take only an initial expander role. It is just too narrow.
Once again, it's my vision of this game aspect. If you have another one, just use it.
Let's stop the OT with this