Welcome to AFF mate.
UA MP is a decent program, but just beware that you do not get class of service bonus miles if you happen to fly business on other *A airlines, other than US and LH transatlantic flights. And there are many complaints of the difficulties involved in getting awards on partner airlines using UA miles.
Another *A program to consider is AC's Aeroplan which gives you *G status after 35 000 status miles. Award availability is decent. And you also get to access lounges on domestic itineraries in the US without having to get RCC membership unlike holding UA*G. But the downside is the lack of Economy Plus access on UA since they abolished it for non UA *Gs.
The beauty of *A programs is there is no requirement for a minimum amount of segments on the host carrier of the FFP you're using to achieve/retain status. But your host carrier-specific benefits on AC like upgrade certificates might be wasted if you do your flights purely on partners. Still worth considering if you want *G status asap and a reasonable earn/burn.
Over on the oneworld side, AAdvantage is a good program for ur flying pattern. The miles earned:miles required for redemption (earn/burn) ratio on AA usually outweighs QFF or anything else in oneworld. You can qualify for AA Platinum via the Platinum "Challenge" with 10 000 Q points on AA flight numbers within 3 months, which is unique to AAdvantage. This is very achievable on the QF flights to LA because you are able to book them under the AA codes. Once you get Platinum, you'll enjoy oneworld sapphire status which involves benefits like business lounge access and business check in across oneworld. You also get a 100% mileage bonus across on all oneworld carriers, which makes the already good value of AAdvantage even more attractive.
You will have to requalify for Platinum via the normal way though (50 000 Qpts annually on oneworld and Alaskan) - this is quite possible by chucking in a small fraction over Economy and fly SYD-SIN or SYD-LHR on BA's World Traveler's Plus cabin which attract 1.5 Qpts per mile flown like First and Business. Not only is it a good compromise between cost and comfort, you also get to avoid the bad accrual rate of discount economy. Like QFF, there is a requirement of a minimum of 4 segments flown on AA to earn/retain status but unlike QFF - this rule is unenforced on AA.
The only thing you miss out on by going with AA over QF is the ability to use QF points to upgrade QF flights. But to put this into perspective, it can cost more using QFF points to upgrade Y-J SYD-LHR return than to use AA miles to get an award in J on the identical QF flights.
I feel it is important to reconcile the ease of getting status and the ease of redemption. It might be far easier getting QFF status based on your flying patterns but as I've learnt through comparing the different programs in detail and advice from several of the more experienced AFFers - that most times the ease of getting status on a program can be offset by its greater cost of redemptions.
You will get like a zillion and one opinions about the various programs and I'm quite sure someone will later chime in with the advantages of going with QFF. It is good that you've already identified your flying pattern, now the trick is to choose a program that actually suits your needs and desires.
Hope I've provided a good starting point and that it was somewhat coherent.