At the end of the day your comparing three of the world's best carriers. That said, I would rate in the following order: CX, QF & BA. That said, if you get a good QF (or even BA) crew, they can be miles ahead of CX.

A quick search on the QF, CX and BA forums should throw up loads of threads comparing them which I strongly suggest you read. As always, YMMV! :)

And then you'll have your own opinions. If your factors are sleep, food and service, then I'd go for QF unless by "service" you mean old fashioned more formal service. I just did a detailed comparison of BA and QF first products based on long haul (11+ hours each) flights last week. It's in the BA forum, and if I knew how to copy the link to the thread, I'd put it here for you. I called it something like "LHR-BKK in F, BA or QF?"

In any case, enjoy. They will both be great, though slightly different from each other.

Nice review and thanks for the info. Here is a link in case anyone else wants to check it out: http://www.flyertalk.com/forum/showthread.php?t=717700

I also thought the other comments in that thread about the BA mattress pad, and taller people being less constrained on QF to be very helpful. I am 6'3" (190 cm) so that is a major factor.

Qf
 

QF less stuffy, better bubbly and the new chief's taster menu. Seating in BA is more private though, but I would go with the OZ folk if you can't travel with CX

They are both very good products that can at times suffer from the vagaries of the people delivering them as noted above.

The clincher for me though is QF as the air vents are so important to me and the BA cabin is always overheated.