Atlanta is amazingly organised but mahoosive...Still they have the transport in place to take you around it with ease as many are there for connecting flights.
JFK is just pants...disorganised, arsey staff and serious lack of facilities !
They lost my bags there once but not their fault. Flight in from Eglin AFB was 2 hours late and my dumb travel department had booked me a connection where I had to pay for the flight back when I got to Atlanta. Credit to Delta I ran to their desk and they believed me that I could catch the plane - which I just did. My bags followed on the next day.
JFK seems to have been designed around Pan Am and if you were connecting to one of their flights it was OK but travel departments were always booking me on the cheapest route which meant catching that damn bus between terminals. Newark airport is surprisingly good for connections and you get a great view of NY.