The priority for business travellers on the JFK-LHR route is to maximise sleep time on the short night flight. BA caters to this market (and so do VS).

If you want to maximise your experience as leisure pax, then take the day flight.

While I am mainly a leisure pax, prefer to maximise my vacation time and fly straight into work on a Sunday night so do want to sleep on-board even when in F.

The BA CR room in JFK T7 while not matching up to LHR T5, is still a great service. Waiter service in the dining room.

If you are in F, it is a not a sleeper service as you do get to order a full meal. They do dim the lights early as other pax may want to sleep but you your personal lighting is more than sufficient.

Interesting choice of query by the Op who posts a question here once a year