I don’t only mean economic, although that is important. As someone migrating from a very rich country, this is the only country in the world with *more* opportunities in my field. It is far beyond every other developed economy in many ways. Northern California alone has more good jobs than some entire developed nations.
But also on a social level, one can’t downplay the important of social integration. It’s much easier to be Anything- and American. Even if you never take citizenship.