I originally read this topic as "Best Airline Promotion" late August, and thought: QF? Surely not

But seriously, I went through a similar decision about 6 months ago. I had a reasonable but not huge number of QF points (>100K) and was deciding between AA/QF.

IMHO there is no generic answer to "which program" and it depends (a) where you live, (b) where you fly, and (c) how much you fly, where to, in what class etc.

In my case, I live in the US and put a lot of Y miles on AA. I will easily make AA platinum (OW sapphire) this year whereas I would be well short of QF gold (OW sapphire) for the same flights. In miles, I get 100% bonus due to AA PLT and this mostly compensates for only getting 70% of the mileage on QF flights. Next year, the decision would be a no-brainer since QF would only give 50% of actual mileage on my AA flights.

Your circumstances may be different though. If you live in Australia and will not make elite status, you are better off sticking with QF because (a) if you're in AA you'll only earn 70% of the actual mileage flown on QF flight numbers, and (b) you can earn QF points through credit cards etc., but cannot earn AA miles. Again, unless you're planning on actually flying some AA flights, I don't know that joining AA gives you much advantage over QF.

I don't know of anyone offering bonus miles for Aust to Europe - they don't usually need such incentives to fill seats.