Good to see finally.
LHR-JFK is timed a little strangely as it seems the aircraft will sit around for 8 hours at Heathrow before departing at 18:10. I'd say a 21:43 arrival into JFK isn't a prime arrival time for a UK based traveller.
I suspect it's slot related.
LGW-JFK is timed better.
Fares are competitive. Mint/"J" for <£1,000 roundtrip. If you're flying from LGW then £290 Y class roundtrip is a good offering.