Both of these are equally doable. I would suggest going to Monash, as internal transfers are generally easier than external transfers, but also pick a course that you'll enjoy if you end up not doing well enough to transfer. If you don't like the business specialist degree, go commerce at Deakin or La Trobe. If you don't like the comm degree at those two unis, go the Monash route, etc.
Also, I highly (HIGHLY) recommend still keeping Monash/Melbourne comm at the top of your preferences, as you never know what'll happen to the clearly-in. It might decrease by 20 points! (I mean, I doubt it, but you never know) A course does not have to be in the first slot for you to get it. All VTAC does is they look at your first preference, check if you're eligible, and if so, give it to you. If not, they move down the list, and repeat. You could get into a course even if it's at the bottom of the list, so make sure you list courses in order of PREFERENCE, not based on your plan because you didn't think your ATAR was high enough.