I know that in 2018, it's very possible that I will not fly AA at all now that they all but ended the AS partnership. AA currently flies from SEA to CLT and MIA and PDX-CLT, routes not duplicated by any other airline. For connecting flights to medium sized and small airports in the south, Midwest, and east that AA flies to, either DL or UA fly there.
So for me, it's AS, DL, WN, and maybe UA. No flying on AA.