Best ISP in Australia? Most people who are into these things will have their own view, but for me it’s Internode.
Simply put, they do what they promise. They do it well, keep me updated of any issues, strive to provide good value for money (their Usenet is free!) and don’t cost crazy money. Over time they’ve managed to get a little more of my cash each quarter, but only because they’ve also delivered better value in return.