NRT-LAX is pretty much comparable between AA and JL.

But if you can, try out NRT-SFO on JL and connecting to SFO-DFW on AA. JL has an upgraded Shell Flat Neo seats on that 777-300 with large 15.4 IFE screens, and a nice Executive Class bar. The JL flights with these upgraded J seats and service give a nudge up than AA.

links of interest
http://www.jal.co.jp/en/inflight/int...cutive/c_seat/
http://www.jal.co.jp/newjal/english.html