You might be better off on NW because 1) most fares on partners earn 100% miles. FB has various cheap fares that only earn 0-50% miles depending on where you fly. L fares is 25% on AF long haul, V on NW and V & N on KL). I believe elite membership of NW in Japan (or east Asia) still gives you complimentary WC membership at the gold level or above. Handy when flying domestic-only on the day, or actually whenever you are at a WC or affiliate lounge.