It all depends on you flying patterns (class & distance)
AA has for many people a better earn to burn ratio
Mid - top tier (Plat - Gold) in QF is not that hard to get
You go for a AA plat challenge to get top tier in AA
QF is moving towards a frequent spender program and away from a frequent flyer program. With QF you can easliy put credit card spend/rewards into the QF FFP.
Air NZ is a poor scheme. Look at BMI or other star airlines