Sorry to be blunt... but this is such a stupid question.
Different unis have good reputations for different areas and different reasons.
Different people have different opinions on different unis based on what they have heard.
You may have heard that USyd is the best uni in Australia.... or you might have heard that a large proportion of the student population are pretentious and snobby.
You may have heard that ANU is a "country" uni... or you may have heard that they have the best law education in Australia.
You may have heard that UTS is ugly and has a crap campus... or you may have heard that they have good industry focused education and a practical approach in a variety of their degree programs.
You may have heard that Macq is the best for actuarial.... or that it is out of the way.
You may have heard that CSU is crap because it is in the country... or you might know that they offer some excellent health science courses, as well as other courses, and provide an invaluable service to regional areas.
Everyone has different opinions on prestige, you can't judge it. E.g. in my home town it was prestigious to be moving away to Sydney or Melbourne, or even Canberra, to go to uni... it didn't even matter what uni it was. In fact, in my home town, actually going to uni is a bit of an honour.
In my opinion, people who care about this so called "prestige" of a uni are uncertain of themselves and feel the need to validate themselves through the name of their university. You should pick a course based on the content and the quality of the course at that particular university. You shouldn't pick a course based on this non-existant apparently all encompasing aura of "prestige"......