Anyone that is saying CX >>>>>>>>>>>> JAL for F has simply never flown both (or at least has not flown both more than once). That is truly preposterous.
JAL F has a slightly smaller seat with less privacy, but the food is heads-and-shoulders better, and the service isn't even comparable (hint: JAL is better). CX wins on bed quality, seat comfort (by a nose), ground lounges, and IFE, while JAL wins everywhere else. JAL even has Wifi so 12+ hours don't have to be entirely productive.
I don't know WHERE this whole notion that JAL F is a downgrade from CX F, but I can't disagree more, and I dismiss anyone who says that they aren't at least in the same league.