Hey Jono. ATAR reqs don't offer a decisive view of university quality. Especially when you have a specific idea of what you want to do. ATARs are done via popularity. Let's say a course has 100 places and 10,000 people apply. Only the top 100 will get in. Let's say all 10,000 people have some sort of score similar to the ATAR. You obviously look at the highest 100 and let them in. By no means is this a direct analogy, but that's the idea. The more popular a course is, the higher the ATAR requirement goes. So, assuming that UoM is better simply because of the scores would not be a good assumption. UoM is definitely good. For other reasons. And the people at UoM may or may not have made an informed decision. They may also have looked at the buildings and decided to go there, so the popularity as aforementioned is not a precise indication.
The Monash philo department is phenomenal.
As far as employment, I've actually seen info indicating a far higher rate of employment for Monash grads. (could be because many more people from Melb go to postgrad? No idea. didn't pay much attention to it tbh)
Honestly, just choose the uni that's going to be quickest to travel to.