Both CX and JL F are top notch, but in this particular case, I would definitely stick with CX. JL 2 (as well as the returning JL 1) is a late-night departure with diminished catering (a light meal after take off, presumably giving passengers more time to sleep, and then a breakfast before landing), whereas on the LAX, ORD and JFK flights ex-NRT, JL serve a full meal after take off with a Wagyu Beef choice of entree for F pax. You may compare the SFO and LAX menus to see the difference:
JL 2:
http://www.jal.co.jp/inflight/inter/...506_201508.pdf
JL 62:
http://www.jal.co.jp/inflight/inter/...506_201508.pdf
I only had caviar after take off when I flew CX872 recently, having had a proper meal in The Wing, but got to enjoy the full meal service before landing (breakfast at 9 pm local time seemed weird to me). This would not be an option on JL 2.