AWS is what we use for cloud provisioning, with Rackspace still hosting some legacy systems. We are moving our workloads off Rackspace as the cost is higher. Azure is a possibility but unlikely as they are as expensive as AWS and offers nothing that we feel is especially compelling as a Linux shop.
If Digital Ocean, Linode or similar offered an Australian hosting option I would be willing to look at it if the cost was under 2x that of a US region, as I could get a similar functionality having SaltStack handle provisioning. However knowing bandwidth and related costs in .au I really doubt many want to go through the cost & effort.
Most of the domestic providers are either too expensive ($40-$80 AUD a month for a 1 core / 1gb instance w/ HDD backed storage & 100 GB transfer), and/or aren't run to the scale that you can have confidence that they will be an ongoing competitive business.