Here are some comparison coverages for Telstra and Optus.
I think MikeL's post with maps sums it up nicely. We went round Oz with Telstra and it was amazing the places were we had a signal - often in remote free camping spots we had a basic signal whereas others on alternative networks had nothing. So if you want reliable communications you really need to use Telstra - OK it's a bit more expensive but you get what you pay for and the latest Telstra plans really are quite competitive.
Renewed my Boost subscription for the next month and I was wondering how you went with changing or updating your internet and phone services.
I hope you were able to work your way through the minefield.