The east to north of Melbourne were where most of the market gardens used to be - Dandenong Ranges, Arthur's Creek, Warrendyte, Kinglake - and the further west and south you go, the less rainfall there is, and the less fertile it is. It is no wonder that the water catchments are all in the east and north. It also gets warmer in the west - the Dandenongs are bitterly cold.
However, these are all places which are more prone to fire - especially the Dandenongs.
The west hasn't historically grown as fast as the east, so it is closer to the city. However, it is the "disadvantaged west" and has always had fewer good schools, most of the industry, and very little in the way of tertiary education. My parents were both involved in education. Things may be changing, but education availability in the west would need to have had a lot of upgrading to be anything like that in the east.
Werribee is certainly a sweet spot in the west, and it might be better than the rest of the west - but it is still hotter and less fertile.
Having grown up in the Belgrave area, I am surprised that anyone would call it "reasonably flat", but it definitely is quite a nice area, and the train line is quite good. The Dandenongs are also more embracing of alternate lifestyle things like aquaponics (although it has a lot of frosts and the fish might freeze).
The north is possibly the best from an educational perspective, as La Trobe University is there.
By the way Dandenong (the suburb) is nowhere near the Dandenongs (Dandenong Ranges, Mount Dandenong).