Kennedy was a breeze for customs, it was the TSA line that was a pain. Pre Check, Clear, and regular at the Delta terminal all dumped into the same entrance of the queue maze, and everyone got the business. Nothing was gained by the line cutting programs.
Also, in said line, agents from LAN Airwys were calling for Santiago passengers. A woman confused that for San Diego, and kept insisting that she was on that flight.
My opinion of clearing customs at DFW is likely soured by having to do so with a sprained and badly swollen ankle.
O'Hare is good if Chicago is your starting or ending point, or if you don't have to clear customs. However, if you're coming from or going to a non-US airline, the number of potential failure points goes up substantially.
My wife and I did our best impression of the Home Alone dash on our way home from our honeymoon. Our flight on Lufthansa was late leaving Frankfurt due to fog, and by the time we landed we had less than an hour to clear customs, take the bus to the main terminal (the tram was out of service), clear TSA, and get to the dead end of the concourse where the United Express flying beer cans load. Fortunately United staff helped us as much as they could, and we did make it.
Going from Lufthansa premium economy in a 747 to the back row of a United regional flying beer can was a bit of a shock.
