So much that millions of people risk their lives or leave their families to come to this country. By this objective metric, it's literally the best country in the world's history.
If you read my comment, I asked if Americans are happier than people in developed countries. How many million Europeans, Canadians or Australians are risking their lives to come to the US?
Sure, if you're from say, Haiti, even the US will look very attractive, but the bar is pretty low there, wouldn't you say?
The reason someone has to risk his life to get to the US could be because the US is the greatest country, at the same time you could also consider the influence that the US in its history has had on other countries so that the life of the people are miserable there.
(e.g. backing and installing dictatorships[1], contributing massively to climate change, ...)
Migration isn't a US problem. Europe has it too. So as a country probably not, but that's also because the US is big and has a large land border to the south.
Immigration in Europe is different. Your immigration influx is not really the kind of force that will help push countries up. If anything, it is a drag. Of course I am generalizing highly, but for the most part you are bringing a new civilization that does not want to become European or help contribute to your growth. Some of your immigrants want to make you change your religion!
In fairness the same has happened in the US recently.
Sure, if you're from say, Haiti, even the US will look very attractive, but the bar is pretty low there, wouldn't you say?