We just got back from HKG using an AA award, with CX on the outbound and JL on the return. Note that our flight on CX was in NBC, not NNBC.

The seats are compareable, the older CX shell model and the JL shell seats. I have not had a chance yet to fly in the new CX seats.

CX's AVOD is miles ahead of JL.

Lounges depend on your oneworld status. If you are an Emerald, JL's new F lounge at NRT is very nice. OK, the food isn't catered by the Peninsula hotel, but good nevertheless. If your only access is to the J class lounge, then I vote for CX.

Food on CX has slipped, while food on JL has improved. I like JL's food better these days. Plus if you like Japanese food, that option is readily available in J on JL.

Service is mostly even. JL is consistently good, while CX will occasionally wow you and other times, it's just OK (but still way above any US based carrier).