I've sat in J seats on all of the above except for 772, 752 and a321t and have sat in F seats on a321t. They were all comparable hard product wise (a333 J seat was slightly outdated but nonetheless comfy). I didn't like the J seat configuration of 788 where there wasn't much privacy due to pax across the aisle facing towards me. I must note that the tray table on 763 was difficult to manipulate but again comfy otherwise.