Have done 2 CX F returns and 3 JL F returns in the last 6 months and in my experience the JL food and beverage is significantly better than CX, especially the Japanese option on JL. I also find the JL cabin crew service to be more proactive which I like.

Seat wise CX is bigger, but both are very comfortable and neither have individual air vents which drives me nuts.

I prefer the JL F PJs to the CX F PJs and I think the JL F amenity kit is better too.

In all honesty neither is a hardship though and both are excellent ways to travel. I wouldn’t go out of my way to avoid CX F over JL F if the routing was better on CX than JL, but if the routings were equal then I would opt for JL.