Edit: After I made my comment his was changed from "cultural harmony" to "cultural assimilation" and there was some more added and taken away, just for clarification.

I changed it for clarity purposes because I realized I would need to make it more obvious what I meant.

And after reading the add on about nationalism, I'd like to add that's really not seen as a good thing in Europe.

Who cares if that's "seen as a good thing in Europe"? It is what it is. Are you here to factually answer questions, or to demonstrate who is more "good?"

I don't want to argue about who is good. But I will point out that although it's true that Europeans don't like nationalism, very few Europeans can actually define nationalism, the difference between nationalism and patriotism, or the difference between ethnic nationalism as has historically predominated in Europe, and civic nationalism such as we have.

And in the article you linked, it states;

The study, which examines 34 countries[...]In the overall score, the US trails—by a small margin—only four Scandinavian countries, Australia, New Zealand and Canada.

You are 8th for social cohesion in the western world behind 4 European countries, and 5th in the western world for ethnic diversity behind 3 European countries, so you can't claim to be better at either.

And in my original comment, I said:

one of its most socially cohesive

...which is what the article says. If you're going to continue to criticize what I said, find a way to do it that makes logical sense.