Without status I'd be leaning towards the LCY-JFK service; unlike some I didn't find the service to be much better than competent on my trip in October. However you are guaranteed a nice seat, a unique sort of transatlantic experience and a quick exit from JFK into the bargain if on BA1.

After that its a toss-up between BA CW Upper Deck (tricky to be sure of without status) or the AA 77W. I'm in the Flagship Lounge in JFK writing this having just done the 77W. Very good for seat and entertainment. The London AC lounge has fast internet, so good for work. With status of course you can lounge-hop at T3 in LHR (as I did for a lovely b'fast this am). Immigration in T8 JFK off the 77W was good actually as the biz cabin get off first of the 300 or so pax; and the ex-MAN flight hadn't beat us in by enough to stack the queue..

Virgin would be different again, I've only done them in economy transatlantic this year so can't comment on present state of UC.