I had no idea you had no choice in Australia until recently.
I made my choice based on the technology of the implants, the available future prospects for software and hardware improvements, the ability of the implant to give me music, the size of the input dynamic range, and also on talking to users to find out their experiences. It's best to ask a lot of questions to help manage your expectations.
I'm really pleased with my choice. I have been switched on for 2 months and music sounds perfect now - and I was born deaf! Amaaazing!