Firstly the caveat that I have not used either the NZ or QF systems as I rarely check luggage for domestic flights.

IMHO Qantas have over-engineered their design with the RFID bag tags. There are a few reports of failure. e.g. I came across a colleague who travelled with one tag attached their carry-on and the other on their checked bag - the system got confused with the tag being used (reading the tag on the laptop case, not the checked bag). Subsequently his checked luggage did not travel with him.

(Many QF elites use said tags on their carry-on, possibly for the DYKWIA factor.)

The bar-code system is simple, portable and proven.