I have been with many providers over the years, currently with Telstra now but in a RIM location so my speed is restricted. Telstra installed RIM due to the low cost of installing the equipment and won the tender. Unfortunately we may never attain ADSL 2+ speeds because Telstra in the typical mind don't care.
I have though been lucky, following up with TIO for every issue dealt with. Their mistake and I have received nearly $1000.00 free internet access over the almost complete 2 year contract.
My shop when it was running used ADSL 2+ Annex M. This is a business speed internet that gave me an Actual speed of 20,000 Download and 2850 upload. Normal ADSL 2+ had a slightly higher download but only 1000 upload. As my wife is Deaf and I use Sign language it made real time video conferencing possible and very clear. It also allowed up 15 simulataneous VoIP calls without dropouts.
Overall though the main issues is support. Telstra quick access to calls is not bad, but have extremely poor training of their personelle, hence the $1000.00 off my access
Other smaller providers are not bad but their wait times are a bit worse. Overall once the internet connection is stable and working for while there is no need to contact support so not a major problem so I am quite happy overall with IINET. Shame I can't get them from my location as the internet access is still controlled by Telstra.