Personally I like DL much better since you connect through SLC/ATL/CVG rather than snowy and far MSP/DTW. You can get 1000 DL miles booking DL flights online at Delta.com and then also get NW/other skyteam miles w/DL. But if you're in DFW, can you find a way to use a Oneworld partner(although they are weak in Asia) and get A A miles?