I'm torn between the options listed in the title. I took JL 4 last Feb in F. But it was a rough flight for the first few hours so I waited until mid-flight for the F class meal. I believe that it impacted the experience. I have an F ticket for JL 10 to ORD. But an opportunity to fly the A350 to JFK, albeit in J, a few days later is possible. It would be nice to try the new plane, but I'm not swayed by all of the new stuff. But the new J is 1-2-1 layout in J vs the 2-3-2 in the 777 which makes the foot print of the seat less of an issue. Flight is next Feb and I'll be travelling to DCA on a separate plane/train/bus ticket. Let the discussion begin.