On the subject of the attitude some Americans have that might come across to non-Americans as smugness or superiority...
This isn't an attitude. In this country it's considered "patriotism", is seen as the duty of every American, and is the result of many years of indoctrination.
I've seen it displayed by people from elsewhere about their countries as well, so I know it's not a particularly American phenomenon. But I think it draws more fire when we do it (in the U.S.) because we are such a large and powerful country.
I don't, personally, think there is such a thing as "the best country in the world." Every country has good points and bad points. Some more bad than good, but I think most of the countries represented in this forum are probably equally good and equally bad.
My 2 cents worth.