I'm probably bias, but WAAPA has produced some EXCELLENT musicians on the jazz front. Guys that are at the high end of world standard, not Australian standard.
VCA here in melbourne has a bit of a reputation for being brutal. I know a couple of people who I consider to be top musicians who dropped out of there saying "it was destroying my soul"
classically speaking I think j_menz is on the money with sydney, one of the better classical students I grew up with elected to study there rather than stay home in perth despite the significantly higher costs/struggle of having to live out of home with no real income...
..not to say WA was bad, I went to an open lesson there when I was 16 and watched a first year student totally nail chopin 10/1 without any trouble in front of decent audience and the public judgment from her teacher.
..and after all that, I really don't know anything about south australia... and maybe that says something in itself? though really there's always more factors. There would undoubtedly be atleast one decent teacher there though