Another consideration is that NW (and CO) give 150% level (but sitll 100% award) miles for B fares while FB gives just 100%. You'll get to PE status faster with NW or CO. Elite bonus is also higher (125% and 100% for PE/GE vs. 100%/75% with FB).
If you can get an address to use in East Asia, you get complimentary WC membership with NW at the GE level and up.