I've lived UK, Knoxville, Tennessee, Copenhagen, Breda (Netherlands), Tokyo & Thailand.
I've spent probably a year in LA as I've been travelling there every multiple times per year for the past 13 years, sometimes for a month at a time. I've been to New Orleans, Dallas, Nashville, Memphis, Atlanta, Charlotte, San Diego, San Francisco - I think that covers it.
The US is not a single culture in my opinion. Knoxville, New Orleans and LA could be different countries. Drive from UK -> France -> Belgium -> Netherlands and you'll see the same kind of differences you see between US States.
The line 'greatest country in the world' I find odd. For sure, I didn't find the US and greater than say - living in Denmark or Netherlands. I am not sure in which respects it is supposed to be so much better.
The stuff about freedom too, I find odd. I certainly had more freedoms in The Netherlands, although it is true that I couldn't carry a gun. Of course, the flip side of this is that the US police are very heavy-handed. I barely saw any police when I was in Copenhagen. I guess with the prevelance of firearms, the police in the US need to be 'tougher'. I can't imagine what it would take to be a cop in New Orleans or Compton. Still, I do remember quite vividly going to watch the freak show in West Hollywood one Halloween. At about 1am, at one end of the street, a line of police cars formed and started moving down the street with the bullhorns announcing that anyone that didn't clear the streets right then would be arrested. It was very aggressive - as if they wanted to cause trouble and it totally changed the atmosphere from fun to fear.
Of course the US is more free than Iran but so is Spain. Being more free than Iran doesn't exactly make you stand out, does it?
So basically, I see few differences. Perhaps someone from the US side could define 'greatest' and 'free-est' country...