I fly around the southeast and Texas, with a few trips to BOS and one to SFO. This year I flew 61 segments on DL with 45k MQMs, and 36 one way trips on southwest with 15k actual miles (no 500 minimum). This year I used southwest in TX, and DL everywhere else and a little in TX. I am based out of MEM and go to DAL/DFW, HOU/IAH, AUS, SAT, XNA, MIA, BOS, and SFO.

Considering a new airline now that DL has made the changes to C+ in 2015 and now 2016.

Extended legroom seating, FC upgrades, and same day changes are most important to me.

Out of MEM does DL, AA, or UA make the most sense for me? Next year I will probably cut back on the southwest flights, concentrating most flying on one airline. Any ideas on how the three programs work for someone with my profile?