I'm just going to come in super late and give my own two cents:
A lot of people have come along and said that prestige=better research opportunities - NOT true. I have worked with someone who was said to be, and I quote, the "most qualified synchrotron x-ray crystallography scientist in Australia". In fact, when I was doing work at the synchrotron, the beamline scientist (the one who literally exists to teach other scientists how to use the equipment), actually said to me that because my supervisor wanted to show me how to use the equipment, he wasn't going to bother, and instead just went through the safety procedures. I would not have been able to work with this guy AT ALL if I went to ANY other university, either.
You'll often find at many universities that regardless of their prestige, there's usually one or two people that are still really good. Even then, if research turns into your endgame, you DEFINITELY don't have to do a masters/PhD at the uni you did your undergrad at.
My recommendation - go to open days, go to extra visits/programs if you can, and pick the university that YOU think has a good atmosphere and that YOU think has good teaching methods and that YOU think has the best student opportunities. I know plenty of people that walk out of first year maths at Monash thinking it's the worst thing they've ever done, I thought it was the best I've ever done. Likewise, I'm currently taking a unit called medicinal chemistry and I hate it - walk over to a friend of mine, it's his favourite unit. Don't let what anyone else says change how you feel about a uni - if you decide Melbourne is the uni for you, go there. If you decide Monash is the uni for you, go there. If you decide vic uni is the uni for you, go there.