You could try a few different airlines to see what works for you. Everyone has different opinions and tastes. For example, I'd disagree with your colleague and say that BA has better food than AA.

On a practical point, something to consider for the return JFK-LHR leg is that you don't have EC/UK261 protection if flying on a US carrier. You would only get that on AA/UA/DL on the leg departing the UK.