Within the country, University of Sydney probably has the best undergraduate law degree. From my knowledge, which is relatively limited, UoM's JD is the most prestigious graduate law degree and allows you the added bonus to be more recognised if you wish to gallivant around overseas flaunting your legal skills/repertoire. If not, and you wish to be a confined to the landmass of Australia, your degree from any university will be fine and would be wonderfully prestigious if from the University of Sydney provided your marks are of a high calibre; nobody will give an iota of a dog turd about your alma mater if you have poor marks.
I am not quite sure why people are so pedantic about these things. Really, if you live in Melbourne and want a prestigious undergraduate law degree - Monash is right there. Competitive, renowned for offering a good course and has produced great legal minds. Also, UoM's model is not all bad; employers want you to have more diverse skills and some students want to spend a few years sussing out their degrees and interests before entering law. Furthermore, in terms of time, I believe it is five years to complete a LLB and it takes three years for your undergraduate and three years for you JD at Uom. Six years with potentially up to three majors in your undergraduate and then a law degree tacked on the end. That's not bad if you want to have a broad knowledge and so forth. The only down side is the LSAT and your maintaining a competitive GPA. If you don't, you can always just apply for graduate law elsewhere. Employers really just want people with skills and can bring what is needed to the table and show some adaptability/community skills.
Take a load off, relax and stop thinking you will be some hot shot lawyer purely based on your alma mater. It takes a lot of work to get to the Bar (if you want to be a barrister) and an even greater amount of time from being an underling to a solicitor/barrister before you have your own reputation. If you are pursuing law for status and what not, you will probably have your nose rubbed up the wrong way when you end up on a lower income than most and effectively shuffling papers as an overqualified paper boy. If you really want it, you have to work for it.