Sorry to use a word that could lead to me being banned, but some of fly in Economy. And QR is not all that on some planes out of LHR - you won't catch me on their 787's or 10 across 777's. So i'll happily fly BA.
However, QR's A350 (gamechanger) / A380's are fabulous.
BUT the point I want to make is the huge increase in options I now have flying East with BA - i.e. Bali is sub £500 in Y, sub £2,000 in J. Other destinations BA don't fly to like Jakarta, Pakistan, Maldives are available are now accessible mainly / partly on BA. It makes huge sense to me.
The only thing I struggle to do is price up WTP itineraries beyond Doha (i.e. in WTP then either in Y or J) - i'm guessing that BA were not so keen to offer these, but I can get via KL, BKK & SIN to many destinations beyond these BA destinations.