Originally Posted by DrCosmic
It's supposed to be a smaller more personal movie, so the villain has got to be someone who can connect with the heroes very personally. I would say either the Masters of Evil or Ultron.
Ulton is the best choice, IMO. While Masters of Evil would be interesting, it's a lot of villains. Ultron could end up being a creation of SHIELD's experiments with the tesseract and maybe some work from Banner and Stark.
Because honestly, there's no reason to bring Pym in, IMO.