QR J class prices out of HKG are insanely cheap. You can fly to destinations in Europe that CX doesn't fly to - aka, we don't have genuine options besides QR or EK for getting there "fastest" - and other ones in the ME and Africa for even cheaper. To Europe $4k USD and less, and to other places sometimes $3k USD and less!

Presumably you can (could? maybe the JV has curtailed this a bit?) also save a lot of coin flying to CX cities like CDG and LHR via Doha, but I haven't done that yet - I'm not a fan of connecting in DOH unless necessary. But I have utilized QR a number of times to places CX simply doesn't fly and the price is very easy on the wallet.