With the way either airline works you are better off starting with the one you don't want to work for eventually. That is if you want to work with QF mainline, go for the AirNZ turboprop job and VV. Once you get a command on the TP and a few command hours apply for the mainline of the other company. This will also give you more of an appreciation of the culture of each and a more rounded view of who you work for, rather than a polarized single view of working for an airline, they are all different.
Also, no matter which one you go for the current industrial conditions means as soon as you have a few hours you can just jump ship to the other without any issues, or move up the chain. There is simply not enough experienced pilots to fill the lower end jobs anywhere at the moment.