If you have the time go for KE. Their A380 is a great experience, since they have a very spacious lounge area at the back of the cabin, and the entire upper deck is business class so it has a very exclusive feel. And personally I always enjoy collecting new aircraft types and airlines.

KE's food is great if like Korean food, though the portions are not huge, and the service is not quite as good as Singapore or Cathay but it's good enough.

Biggest disappointing area with KE is their lounges, which are nothing special. Certainly wouldn't bother to get to the airport early.

ETA: I suppose the one downside to KE is that you have to schlep out to NRT for your departure, vs. being able to depart from HND on DL. So, that may or may not be a problem, depending where in Tokyo you're staying and how you were planning to get to the airport.