I really liked both lounges, and I think they're very comparable too, I feel the Qatar lounge is a no brainer if you're traveling on a oneworld cabin in J with no status.
Both lounges had high quality a la carte food, however the QF lounge was Asian/Western fusion focused and the QR lounge had your typical upmarket classic Western fare, with some classic Middle Eastern dishes thrown in. QR wins in the self serve department though.
When I went, the QR lounge was very quiet despite their being quite a few oneworld flights departing within a few hours. Having said that the QF lounge was also quiet, although I visited that one earlier in the afternoon.
Decor and seating seemed equally good IMO. The walk from the QR lounge to my gate for a QF flight was a good ~10 mins longer then it would've been if I had used the QF F lounge.
Overall I'd probably choose the QF F lounge while I'm a WP. However, if I ever lose OWE status it would be the QR lounge for me.