Originally Posted by CheVive
If you fly BA to the US and back, you can't earn or redeem AA miles on those flights (unless I guess you take the AA codeshare from MAN).
As far as I understand it, in oneworld, you can't use one airline's ff miles to upgrade when flying another airline in the alliance (Star Alliance does let one do this).
For those reasons, I'd suggest just going with BA.
QF is another choice.
Some transatrantic restriction is not applied.
By the way, CX's asiamiles program can upgrade AA/BA/KA round trip flights. It is one of exception.