I fly into the US from Argentina 10-12 times per year, MIA has consistently been the most frustrating, JFK moderately frustrating, and DFW the least frustrating. All have sucked on more than one occassion though.

I'm a US citizen and usually fly alone, I had to wait over 90 minutes in DFW once 2 year's ago because my flight landed right after a couple of jets and just dropped off 5-6 hundred returning troops. The real killer was that I had already been in line for 20 minutes when they moved the troops ahead of everyone else, I almost beat them

I had to wait over 2 hours in DFW once when entering with my wife and kids, we had to wait in the foreigner's line because my wife is Argentinian. We landed minutes after several other international flights, the foreigner's line was all the way out to the bathrooms in the hall.

I'm glad I finally singed up for Global Entry a few months ago