Last year I flew EDI - New York JFK with Delta, and I was very impressed. Good on time service, modern cabin with complimentary drinks, meals and seat back entertainment.
Flew back with AA and the experience was not even remotely as good as it was with Delta in their very 'well travelled' 757.
The current 11am flight time is also ideal, as the airport is quiet, and you don't need to get up ridiculously early either.