I was in pretty much the same position, and ended up choosing Monash. Quite a few people I know who had the option of Chancellors also chose Monash over Melbourne.
I had Med firmly set in my sights, so getting to study it from day one, and in a course 2 years shorter was a big plus. I was also not keen on studying some of the Biomed subjects focused more on chem and physics. The Monash course obviously deals with clinically-focused content right away, and it's been great learning about physiology, anatomy, pharmacology etc, as well as about the broader social and political context of medicine and the healthcare system. Another great aspect of the course has been learning clinical skills every week. The cohort at Monash is very very close-knit and supportive, and no experience in the health sciences is no problem at all - everything you need to know is taught to you, and he only assumed knowledge is very basic chemistry.
In my opinion, Monash med is a great option if you definitely know you want to study medicine - its scholarship ends up being worth roughly the same at Chancellor's, you get to study medicine right away, and it's 5 years. However, Monash med doesn't offer much opportunity for breath (except for a Diploma of Liberal Arts or Languages) - so Melbourne would be good if you don't have a concrete ambition to study med or if you want to experience other study areas etc. You just have to be wary that, with Melbourne's interview in year 3 now, getting into med isn't guaranteed - and honestly it would suck to not get in after the 3 years of study.
All the best with whatever path you choose