For DL, DTW and ATL are major hubs, which CVG is still a focus city. PHL is currently a hub for US. Where are you based?

DL seems to have its act together on operations (few delays/cancellations and most employees are nice to passengers), but people criticize its FF program for lack of award/upgrade availability. DL has also announced some major changes, including spend requirements for elite status.

US/AA are just starting their merger. It remains to see how operations will be affected, although employees seem to be unhappy. It also remains to be seen how joint FF program will develop and, in particular, if/when they will follow DL and UA.