There is no one right air-conditioning system for the Canberra climate. The right air-conditioning system for you will depend on your budget, size and style of your home (i.e. larger homes may be better suited to ducted systems, while apartments may only need a split system), and cooling preferences.
That being said, evaporative cooling can be a more comfortable option in Canberra compared with more humid cities such as Sydney and Brisbane. This is because evaporative coolers increase humidity. In a dry climate, extra humidity can have a cooling effect.