For a major airport, I’d vote Fiumicino as the worst - crowded and very confusing. When they were doing construction on De Gaul it was pretty bad, too. Johannesburg is really nice. Hong Kong is cool cause you can get on a train without ever leaving the terminal and be in the heart of downtown in 20 minutes - Blade Runner meets Disneyland...
One good thing about the *old* HK airport (Kai Tak) was that it was about a 5 minute cab ride from the Star Ferry terminal on Kowloon.The train to and from the city *is* pretty impressive though.And it's all courtesy of the Brits who got things underway just before they left.Of course the Chicoms won't tell you that.