You'd have to say that USA airports have improved over the past decade.  I mean, LAX is even tolerable now, esp with 100% airside interconnection.  DFW is efficient for getting around but doesn't rate much in other criteria. Lounges - the AA ones are OK, maybe good on a good day and if you have Flagship First dining.  Haven't been to non-OW ones. Non lounge activities - those dreary shops.  A good airport must have a good landside hotel with covered and level-walkable from arrivals/immigration.  I don't have 100% confidence in USA airports' ATC safety, in general - or, put better, lower confidence than other western airports.
Obviously any place with e-gates goes up the rankings.  CHP recently had just 3 manual booths for hundreds departing!
I do think security set-up is important in ranking.  The length of wait, the clarity of what needs to be taken out, even the attitude of the staff there.  USA airports generally rank lower on those ... you can get some downright hostile agents there (and not just there).
Security at the gate - Changi - I was going to say how I groan every time I approach it, but then I realised I do that for any security and with Changi - well, within 5-10 mins of security you are on the plane with a bevvy (assuming J 

 ). Changi airport is just 
pleasant to be in and I can't recall it ever feeling crowded.  Early-check in at the Jewel. Immigration - well, choose which e-gate you want.  SQ lounges can get crowded (except TPR 

) , OW ones - just wow for the number and variety.
Certainly Asian airports seem to get it right.  HKG very very good, but gets a bit crowded when I've been there; city check-in, and the lounges - wow.
	
		
	
	
		
		
			Let the people who have no interest in looking at the shops actually go to the gate and wait for their flight and free up space around the shops so that the people who do want to look at the shops and buy things can actually do so without getting stuck in a maze of people just standing around taking up space.
		
		
	 
In my investment banking days, I was on the team advising a buy-side consortium, looking at DRW amongst others.  
Awful airport! they said. 
Low value. We'll have to spend a LOT on changes if we buy it.
 Um... why?...everyone thought, - it had a great new-ish terminal, very efficient, a breeze from check-in to gate.
Answer:  
At any airport we own, you can't go from check-in to the gate without passing at least 50 shops!