ATL is much better choice than CVG:
1. longer flight time gives a precious extra hour of sleep
2. much less chance of delay for lots of reasons
3. far better/faster INS/customs clearance at ATL (they built a great facility for the Olympics)
4. more connecting flights (if you are delayed)
5. sometimes better food catered in ATL (it should be identical, but JFK consistently has worse food, and ATL better food, while CVG is in the middle; has happened too often to be coincidence).

I like CVG, but it is a 2nd class International hub for delta.