I love America--if I'm being honest, I love California more, but that's just splitting hairs. Though I loved living in Europe, I'll take my home town any day.
The thing is, I don’t hold much stock in this affection. I know how capricious and random my love for my home country is. Though I love my country, other people don't. And this is okay, because America isn't objectively any better than any other country.
The most accurate analogy is sports teams. I love the Los Angeles Lakers and Michael C loves his Bruins. We both love the Anaheim Angels if they make the playoffs. I hate Notre Dame, the Yankees, and every Boston area sports team. But I also realize no sports team is objectively "better" in terms of character or intrinsic quality, no one is wrong for lovng their team.
An example. My brother and his fiance went to UCLA. A good friend of our family went to USC. During a car ride, both got into argument (I may have started it) over which team had worse fans. My brother's Bruin-ite fiance claimed USC fans were the rudest she had ever seen. The Trojan claimed to have seen UCLA students make a lewd gesture towards his USC parents. Both claimed the other sides fans were vulgar and rude; both had virtually the same anecdotes.

Anyone on the outside can see the truth: neither school has better fans. They are all just fans.
Why do we love our sports teams? Most of the time it's because that team is the closest to you, or your parents rooted for them, or you went there for college. If you live in Southern California, then you probably love the team from the area you grew up in. Or you root for whoever is winning. In New York, you instinctively hate on your local teams if they don't win a championship.
In other words, the reason you love your sports team is completely random. Just like your love for your home country.
I love America because I grew up in America. It is familiar to me, and my pleasant memories of it from my youth make me love it. But I didn't choose the country I was born in. It’s one thing to say America is the country for which you have the most affection, but it is another thing altogether to realize it isn’t objectively the best.
CS Lewis made this point once, and I’ll paraphrase it: do you think it is an accident, or divine providence that 99.9999% of people love the country they grew up in?
Like I said, think sports teams. I love the Lakers and hate the Celtics, but I realize this love is irrational. Neither team is actually better or worse than another. Sure Kevin Garnett is over the hill, but I shouldn't hate him for that. I hate Florida, but I felt bad when Urban Meyer had heart trouble. We care about our sports teams, but not in any meaningful way.
In the end, I wouldn’t kill over the Lakers, and that's really the main difference between sports teams and nations.


“completely random” would mean a lack of any definite plan, purpose, or pattern. You’ve already provided reasons (quantitative and qualitative) why people love certain schools or teams.
One criterion we know about is simply that some teams are better than others. There are various methods of analysis including the use of numbers that are amenable in terms of determining objectivity.
The repeated reference to America as not objectively the best or any better reads as a bizarre indulgence in literary corporal mortification. Simply asserting this position does little to help its veracity. Also, an innate challenge to objectivity almost certainly would need to come from either a Constructivist or epistemological vantage point.