You know, for not making the list, I think #4 sounds pretty damn awesome; child soldier powered by an illicit and volatile super-drug that turned him into a living weapon, and the ideal pilot/battery for a suit so precarious in its make that it has killed all other would-be pilots, or severely injured/disabled them. Plus this 'generic German scientist' could be a bigger deal, like perhaps the infamous Arnim Zola in HYDRA. Those guys have a way of weaseling into every little crevice they can find... 

So tbh, especially given our overall lack of techheads thus far, I'm actually super game for #4! But after some more thorough explanation on #1, I actually lean towards it closer than #3 if 4 is off the menu.