Well from the PAX perspective, both Melbourne and Sydney suffer badly from one aspect. The absolute GREED of the car parking operators!!!!
From that perspective both fail.
Melbourne also fails miserably when you want to pick up a PAX at arrivals. There is no provision for 5 or 10 minute parking where you sit in the car and wait for the PAX to walk out of the terminal. Sh!t even busy airports like LAX & O'Hare provide that!!