NZ_Flyer, it depends on what you want to get out of your program. QF is the easiest program to obtain status. One (optimized) DONE4 will give WP plus Partner Gold.
But the earn/burn ratio for award flights is shocking on QF an might get even worse in a month or so (with the introduction of anytime awards).

One thing you should also consider is that you need to take 4 flights with BA or QF in order to maintain status. This policy is enforced by both airlines.

If you want to look at an alternative to QF, then AA is your best option. They have a great earn/burn ratio, it is mediocerly difficult to get status but they have a fantastic earn/burn ratio and give upgrades to their elites. And they do not enforce the 4 flights policy (yet).