Originally Posted by bhomburg

Doing this flight once a year, there's no need to worry about QF points expiry. The QF points expiration counter is reset by any activity once every 18 months only, and one flight within 12 months will keep all points safe from expiring as long as rules don't change.

The two cheapest QF booking classes earn only 25 % with AA, and the six fare classes one and two steps up the fare price ladder earn a still meager 50%. QF economy fares earning more than 50% on AA get horrendously expensive. I've flown in business on MH for less money than QF wanted for a "H" coded economy ticket that was far away from being full fare!
I don't think QF offers an affiliated cc in the US. AFAIK their relationship with Amex is limited to Australia. Check Amex if they allow MR points transfer to QFF for US-based members, though.

I would switch to AA only if you'd be willing (and able) to play the credit card game in the US. The miles generated by AA (and US! US miles will become AA miles at one point as the merger progresses, and in the meantime applying for US cards just doubles the opportunity for sign-on boni. US cards don't have a spend requirement, either) cc activity more than make up for the lower earning on AA on one flight a year. If you do not want or can not do that, stick with QFF.