What's so bad about breadth? 4 subjects isn't going to kill you and you might actually enjoy taking something less full on. They don't have to be history of english literature if you don't want them to be
You can do breadth subjects at Monash if you wanted to. They are completely optional which is why I would pick that over the Melbourne Model.
If you were considering a career in research, or at least doing a postgrad degree, then sci scholars would be better as you could set up your undergrad degree to prepare you better for postgrad.
You should do sci scholar over science at melbourne, both of them would look equally good on a resume (hence prestige won't matter) and if you get into the sci scholar, then you'll be given a scholarship and thus will be paid to study. There are other factors such as the flexibility (which has been really good to most people I know doing it, seriously, being in sci scholar, you could do a third year subject in first year without meeting any of the prereqs, they'll let you do anything)