I've taken both DL 744 and KE 773 service to ICN. By far, I would prefer the DL flight. Most reasons have already been mentioned, seat quality, aircraft (config and, yes, temp was too hot on KE), wine, etc. The only edge KE had was they served a few authentic Korean meals. From a service standpoint, that's dependent on your preference. I much preferred the Delta service--it's a bit more down to earth and friendly while the KE is more formal and polite.

Just my 2 cents worth.