In my opinion it's Asiana Airlines (A380 service) - I did this route in 2014 with OZ. There is no better economy class in my opinion, and the transit airport at Seoul is really the best, most efficient in NE Asia. I book on either Orbitz or Priceline - both excellent. I call the airline later to book my seats and to request the free hotel (only when I have a lengthy transit in Korea).

I have also used EVA, but Asiana is considerably more comfortable - both have excellent food, but the service level on Asiana is far superior.