Star Allinace member Asiana has nearly always been great for award space. I’ve long had good luck with their New York and Chicago – Seoul flights as well as Los Angeles. In fact both New York JFK and Los Angeles are good not just for business class awards but for first class, too.
And if I really need a business class award to Asia, I know I can count on Asiana from San Francisco or Seattle to have space. These are just ‘go to’ flights for using miles.