Seems that most people are comparing the FF programs. Don't forget - you actually have to travel on the airline! Based on personal experience, there's a reason there are so many DL DMs floating out there - it's just a better-run airline right now than its counterparts. I've flown every significant domestic airline in the past year, and AA ranks above only NK for me (not kidding). I actually think US is a better airline as far as travel experience, so if AA were to become more like US, it would actually be a positive, based on my experience. DL has a more comparable travel experience to B6 and VX (slight notch below both), and a better travel experience than all its legacy competitors at the moment. To be sure, DL has significant room to improve, but anyone who wants to move over to AA - thanks, more room for me!