Iran or Mexico? Which is a bigger foreign policy and security problem for the US?

I can't get rid of the impression after all the Iran hysteria in the media that it all plays in the hands of the Iranian hardliners. That gives the opportunity to pose as saviors against an imaginary American aggression. Anyway who cares about Iran. They have a nuclear and missile research program but are far from producing anything useful and it is possible that if Russia pulls the plug it will all fizzle out.
On the other side Mexico seems to slide if not straight into the hands of criminal cartels then in the best scenario into anarchy. Mexican drug cartels manage to kill more Americans than any Iranian connected group and frankly I believe that if the Iranians were anywhere near a nuclear bomb or a proper missile the Israelis would have bombed them by now.
I believe democracy and development in the world is of primary concern. France, Germany, Japan, and even China have far more developed nuclear and missile technology yet pose no threat (I simply don't know where to place Russian in this context: better technology than China but less development an I don't know how democracy in both countries can be described if at all). Why then Iran is a threat? Why Mexico? I believe because they are not democratic, not developed and most important their development is not tied up with the US economy the way China, Europe and Japan are.