Asiana
Last time I flew to Paris with Asiana I had a free overnight
hotel in Seoul. Decent hotel & was able to go for a walk,
but very cold. Shorter stopover one can take a tour, cold
weather gear provided & I believe you don't have to clear customs.
For me, I'd get to Bangkok or Kuala Lumpur and then onward
with AirAsia. Low cost, but you can get a lie-flat bed.