My worst experience with airports has been Atlanta, Georgia and Oliver Tambo, Joburg.
Atlanta took almost 2.5hrs to get through immigration which was annoying but just meant I got to my hotel later.
At Joburg, however, it was the check-in that took forever. I almost missed my internal flight until a local told me to just ignore the queue and barge my way through everybody… They were right and nobody complained so I made it by the skin of my teeth 