Cards I can think of that are specifically useful to AS flyers:

* Starwood preferred guest: earns 1 starpoint per dollar spent, and 20k starpoints transfer to 25k AS miles.
* Citi prestige: boardroom access via priority pass, also admiral's club access when flying AA same day.
* BA card from chase or ultimate rewards earning cards to transfer to avios and spend fewer points on shorthaul AS flights. (Also Amex points, but they devalued the transfer rate)

that's off the top of my head...