I don't know, I would much rather be in Bratislava or Bucharest than Pittsburgh (the only one out of your list I've been in) in terms of quality of life, income, and opportunity.
Having lived in Bucharest for most of my life (and in many other countries as well), I recommend Cluj if you really want to live in Romania. Bucharest has nice areas if you have the patience to look for them, but its traffic, noise, and pollution are unbearable
But, I don't think this holds up if you discount the novelty factor. In purely economic terms, you'd want to be in Pittsburgh.