Not strictly a OW carrier, but you could consider Turkish Airlines. AA is a partner in their FF programme
Miles&Smiles
That is what I use for AA miles that I cannot credit to BA, plus I have had to use TK on occasion in any case. Personally I quite like them and 25k miles to get a business class reward ticket across Europe is not bad!
You will also get more FF points for your miles with TK than AA by my reckoning: AA give you 1.5 points per mile in First, TK offer 2 points per mile.
I shall hopefully be topping up my account courtesy of Expedia later this year. ^