If you are looking at electric jacks, there are two brands that I know you can get in Australia; Happijac and Reico Titan.
In my opinion, the Happijac jacks are not as good as the Reico Titan jacks. I looked at both brands very closely before deciding on getting the Reico Titan ones myself.
As far as I know, the Happijac jacks are rated at 680Kg each (1500lbs) and the Reico Titan jacks are rated at 1100Kg each (2500lbs). Both brands mount to the camper in a similar fashion, but the Happijac's use square tubing whereas the Reico Titan jacks use round tubing. From memory, the foot on the Happijac jacks is welded on, whereas the Reico Titan foot is removable.
As you might expect, given the additional capacity of the Reico Titan jacks, they are heavier than the Happijac jacks.
Here there is not much difference in price between the two brands, both being around $2.5K for the complete kits (4 motorized jacks, controller, remote etc.), so it really comes down to which ones suit your setup best.