Obviously you should look at the earn and burn rates of each programme, and make sure you include all taxes and surcharges that you will be paying when comparing them.

Qantas has a requirement that you take 4 qantas flights a year to be eligible for status qualification. I don't know if AA has any similar requirements, but you should check in case you would have trouble still meeting them in the AA programme anyway.

Also, if this is a long term relocation or just short keep in mind any lifetime status opportunities in each programme.

Advantages of the qantas programme will primarily be local partners, both non-flying and also flying partners such as jetstar (who are not oneworld) etc.