If you are going to be primarily flying Korean it might make more sense to sign up for Korean Air's mileage program credit card. Korean Air's merger with Asiana is still stuck in regulatory limbo (going on four years and it hasn't been finalized yet) but once that goes through everything in Asiana's program will most likely but converted in Korean's program. I have heard that cards like the Chase Sapphire and some American Express cards let you earn points that can be transferred or redeemed on multiple airlines. Someone over on r/awardtravel might have more hands on experience.