Normally choosing between CX and AY is a no-brainer. But this time it's a more difficult decision. I've never taken AY longhaul, and could use advise from those that have.

I'll be traveling on a DONE3 RTW trip in September. The last portion is:
AMS-KIX-TPE-HKG-BKK-HKG-SFO.

For the AMS-KIX leg I can take AY via HEL or CX via HKG. If I take CX, the trip is 4 hours longer. Also, if I take CX, I will have 5 intra-Asia flights and will have to use about 35K miles or pay $400 since 4 is the limit without additional charge.

In your opinion, is the extra 4 hours and miles worth it?