Do you believe America is the Greatest Nation on earth

[Middle-aged Europe]

The fact that Old School Republican had to further define "at what" the USA is supposed to be the greatest nation after having been asked so by another poster shows how meaningless the question really is. The statement "America (you can insert any other nation here as well) is the greatest country in the world" is based on emotion and sentiment and not on objective empirical evidence.

There are probably numerous criteria how to measure the "greatness of a country" (status of civil liberties, level of corruption, number of incarcerated journalists, GDP, GDP per capita, literacy rate, life expectancy, suicide rate, crime rate and on and on) but is highly unlikely that any single country is ranked 1st in all of them across the board.

My often used standard answer to the question is "Norway is the greatest country in the world" and that is based on the fact that Norway usually ranks 1st in the Human Development Index (HDI), with Freedom House and in the Democracy Index. But neither does Norway rank 1st in all surveys either nor would it retain the spot if the criteria were changed.