You "may" be a little higher up the queue in the event of oversales, irrops etc if you are a customer of the operating airline. I also understand that the cancellation fee on BA is £35 v $25 on QR. You can also cancel until 3 hours before departure on a QR award, but 24 hours on BA. I don't know if the seat selection and various airline and booking fees are the same on both.

Some people prefer the comfort of home, but QR own a big chunk of IAG (and so BA) so maybe it's not so far away anyway.