Optus suck
vodafail are pathetic
telstra suck and have there head up there arse, but there coverage is #1
Telstra will provide coverage and reach - just do not expect too much with customer service since they offload most customer services offshores
Vodafone - failed last time when they are migrating Hutch to their network, with this I point it to human error/fault very poor project management, but they care about their end users with a lot of upgrades going on. Bang for your money
Optus - they used to be good and there were quiet for awhile - if everyone noticed there are a lot of new telco providers popping up? do not be surprise a lot of new MVNOs within Optus network. In addition, last couple of years they let off a lot of jobs and merged job titles. So service will go down the shits soon even they provide cheap rates.