I prefer 3J.
I like being on the right hand side of the plane as your view out during boarding is not obstructed by the jetway and, when flying into JFK (my usual airport), you are on the best side to appreciate the Canarsie approach to Runway 13L, with its dramatic low altitude turn onto short final (closest I'm getting to the Kai Tak experience). Row 3 is reasonably well situated for FEBO and is not right next to the J Galley, which, as noted above, is often a source of noise. It is also further from the F bathrooms.
It also makes the best advance seat assignment in that it is a good hedge against the lack of predicability about configuration. Seat 3J is a very good seat on the Coffin 777s as it is by the window (good for me), has a personal storage locker and, as Seatguru notes, is the only row not diretly near a noise source. Of course, there is no guarantee that that seat assignment will stick if the configuration changes, but it is the best you can do.