As for J class, (disclaimer: I have not flown on 35G yet!) I can't be bothered to read through all the pages in the A350 general thread but I remember there were some initial posts with pictures that showed how the bulkhead seats had smaller/tighter footwells compared to the other seats, contrary to the 777/330s. So really perhaps 16A is the 'best seat' by a small small small margin then.