As a second army I want to incorporate the new Adeptus Mechanicus models (as an IT person I too praise the omnissiah). I would like to take them as Allies since they lack a HQ. So the question becomes should I pair them with the Imperial Guard or Militarum Tempestus? I wish I could make a Adeptus Mechanicus army by itself, but without a HQ I don't think that would be possible. Just brainstorming for now, but the new models and codex have me psyched to do something with them. Or could you do something with Imperial Knights to make a stand alone army?

(side note: I have not Imperial guard or Militarum Tempestus I am completely starting from scratch)