Delta or Northwest?

I've only flown Korean Air (once) or Northwest (multiple times) on the transpacific flights. Is Delta decent? Problems with delays or anything else? The entire trip with Delta is an hour shorter but the longest flight will be 3 hours longer. (Delta=Busan-Narita-Atlanta-Tampa; Northwest=Busan-Narita-Minneapolis-Tampa.) Delta is cheaper. Advice?


Update: I assume everyone's satisfied with Delta's service or maybe you get to fly really nice airlines like Singapore Air; anyway I'll go with Delta.