You will only get a seat with Qantas if there are still some available for FF's. In 10 years of membership of the Qantas FF program, I have only once been able to redeem anything from Qantas and that was an upgrade from economy to business, Hong Kong-Sydney.
The Velocity and Asia Miles programs guarantees you a seat when booking if there are seats available and if you check out the partner airlines, you will get just about as much coverage using them as you will One World.
Why am I suggesting the Velocity program as against Qantas? Points can only be transferred to Qantas after 31st March if you agree that all points gained on your credit card are transferred to Qantas. They want the lot regardless.
I once was a Qantas shareholder, I have supported Qantas over the years and used them as a preferred carrier. Owing to their attitude about points transfer and the new system introduced by them, I am afraid their greed and lack of ability to supply rewards seating even though there will be empty seats on the flight has killed my loyalty. Qantas has shot themselves in the foot.
I have now joined both the Velocity and Asia miles programs. I can transfer points to either program as required and find that if there is a seat available on the flight, then I get it and that is not a stand-bye situation.
When comparing points required, generally Virgin require less points than Qantas when flying within Australia and to and from New Zealand. With the Velocity program partners flying internationally, they are on a par with Qantas and sometimes less required. Today I booked a return flight with Virgin Atlantic Sydney-Hong Kong return business class, points required, 68,190 and have guaranteed seating. This flight is for 5th May out of Sydney and return date open. Qantas requirement for the same flight, 120,000 if seating available. No guarantees and must have return date.