You could also consider doing a concurrent diploma in computing or maths alongside commerce at UniMelb. Even without it, you could choose to study a lot of maths/CS heavy subjects at UniMelb through breadth subjects.
I would say that UniMelb somewhat one ups Monash when it comes to industry connections and opportunities (eg. more options of clubs/societies, case competitions, networking events etc). Content wise I can't imagine them to be too different.
Obligatory disclaimer that I went to UniMelb not Monash, so please take with a grain of salt.