Lol Sunbury is a disgrace. The real answer is New Gisborne and Willowbank estate. Not really many places to avoid.... theres older gisborne where its a bit cheaper and New Gisborne where its a bit more expensive. But its not like the city where there are definite areas to avoid for safety purposes. if you want to be safe and not robbed, stay out of Sunbury and Melton.
Mulbarton and the Gisborne village areas are the posh areas at the moment. There are new developments around brooking rd which are quite nice too and it’s cheaper. Gisborne is a small, safe, and quiet town. The tree line streets and parks are gorgeous. New Gisborne state school is excellent and it rates over 92 on naplan results. Holy Cross is also an excellent school and cheap for families. If you had enough of traffic, stressed people, noise and crimes , this might be a good place for you.