What are your goals? Do you want to upgrade some of your trans atlantic flts or use the miles for free travel? If free travel is the primary motivator, do you prefer oz travel to other destinations?

If free travel to oz is the objective, UA may be a better choice than AA. I generally find award travel on UA to be easier to get than on QF (though QF's increased capacity may have changed this now). I prefer Econ+ on UA to AA's MRTC though personally I'd like to use the miles to upgrade to business.

On AA, with the mileage you'll rack up, even if you don't reach EXP you can still get plenty of mileage based upgrades. On international routes, AA these days release more R inventory than C inventory (EXP upgrade certs as opposed to mileage based available to all) but on NYC/JFK I see a lot of mileage upgrade inventory. UA is not too bad either and as others have said there are not infrequent opupgrades.