Here are my thoughts in regards to this.

AA has two main advantages:

- the earn/burn ration is much better than QF
- You get lots of upgrades as an AA elite.

In your situation I would most probably still stick with QF for the following reasons:

- You can get extra points through your credit card in Australia which compensates the earn/burn disadvantage compared to AA
- It is always good to be with the program of the airline you actually fly.
- Once you start doing some segments in the US you can look at buying YUP fares. Because status on QF is very easy to get, you will be a SG or even WP in no time with those fares.
- QF status will give you lounge access in the US whereas AA status will not.