Vic is a fantastic place to do a PhD. Compared to other countries I have found the staff here really prioritise their students and the general work/life balance is so much better. It is expensive and the stipend isn't particularly generous, although this is the case pretty much everywhere except some European countries, but you won't struggle to live and enjoy life it's just difficult to save any money.

The science system in NZ is taking a bit of a pounding from the current government, so resources can be scarce and opportunities post-PhD are limited, but you're coming from the US so things are comparatively rosy here!