Good afternoon!

I'm having a hard time finding the best way to use miles for a roundtrip in business class from Los Angeles (LAX) to Ho Chi Minh / Saigon / Tan Son Nhat International (SGN). I have American Express Membership and Marriott Bonvoy points I can use and transfer. I tried calling in to Japan Airlines and Asiana but didn't get much help at all after their 1.5 hr waiting period.

Would any of you happen to know which airline would be best to transfer the points to for redeeming business seats for a flight from LAX to SGN?

Thank so much for the help and tips!