The one criteria that makes the USA the "best" ironically is its form of government that few Americans are aware of - since it was abandoned in the 1820s.
In the
republican form, the people are sovereigns - until they surrender that sovereignty. Whereas in the rest of the world, people are subjects of their respective governments.
SUBJECT - One that owes allegiance to a sovereign and is governed by his laws.
...Men in free governments are subjects as well as citizens; as citizens they enjoy rights and franchises; as subjects they are bound to obey the laws. The term is little used, in this sense, in countries enjoying a republican form of government.
- - - Black's Law Dictionary, Sixth Edition, p. 1425
[Note: there is only one nation with a republican form - which is not synonymous with "republic."]
GOVERNMENT (Republican Form of Government)- One in which the powers of sovereignty are vested in the people and are exercised by the people ... directly ...
- - - Black's Law Dictionary, Sixth Edition, P. 695
Tragically, this generation will probably be the last to live under its vestiges.