I've landed on international flights at just a few US airports: JFK, IAH, MIA and DTW. DTW has been by far the best experience, owing to the friendly and courteous CBP staff.

CBP staff at the other airports has ranged from sullen and unhelpful (IAH, MIA) to surly and hostile (JFK, routinely and reliably so). JFK and IAH both inserted unreasonable and pointless delays into the entry process. I will avoid them whenever possible when traveling out of the USA.