Ok, so the more I think about it the more I think. for literary purposes, Changeling would have the scariest of all aliens.

I'm looking at it from the perspective of giving an excuse to create scary and horrifying antagonists for a game. so regardless of possibility of gestation, I'm just handwaving it and assuming that a Facehugger did catch one and the resultant Xenomorph is different for each.

So I'll look at each one in brief but I don't know much about a few of the splats so really I'm stretching this whole concept pretty far so that I can get an interesting amount...