I flew one way in each a while ago and I would say that if they are the same price I would go with QF particularly if it is the A380 with the good IFE. If BA is cheaper I didn't find anything wrong with it. It depends what you're after, if the food side is important QF is for you however if you're like me and barely eat the onboard food BA is more than adequate.

Downside of the A380 on QF was the annoyance of having to grapple with the footrest and screen everytime I wanted to get up which is often for me as I am a restless traveller. I also found that with the screen being in the arm the armrests were wider so if you were lucky enough to have an empty seat next to you if wasn't comfortable to put your legs over unlike on BA.

So, in summary () QF if you want nice food and they are the same price, or BA if it is cheaper and you don't give a stuff about the food and service.