I've flown all four and will tell you that JL and NH are far superior than the other two. The service on the Japanese carriers will be much more polished and consistent. The food out of HND will be near-restaurant quality. DL and HA are hit and miss at best. The DL hard product is out of date but does have all aisle access unlike HA. The only downside with the Japanese carriers is you might get sauna temperatures in the cabin. You've been warned.