So it is a bit complicated:

If you pay with your Avios Credit card you will get Avios for the payment of the flight. Where you credit your miles does not matter.

I use for example my Lufthansa Credit card and I get 1 Mile per Euro I spend on all spendings. These include BA and QF Tickets.

For the flying it gets a bit complicated.
1) Find out your booking class of the flight.
2) Look what factors these flights will get (100%, 25%) on the QF and BA website.
3) Look up the cabin bonus (for Premium Eco and up).

4) Think about Status - depending on your flight profile, thing about the possibility that you can attain/retain a Status.
Be careful: You need 4 Segments in each program on own flights (QF needs 4 QF coded flights, codeshares allowed, BA needs 2 (for Bronze) or 4 (for Sliver and above) flights on BA - NO Codeshare allowed).

5) Thing about the reward you want to get with your miles in both programs

6) Chose!