Steve - there is really only one place to find out the answers to your question:
http://forums.whirlpool.net.au/
Choice really depends on your locality - so use the info on these forums to help you to decide. There are rating indicators and lively discussion on each and everyone's favourite and least liked ISP's.
Every story you get will be different.... so look up each ISP you have heard discussed here and see both the good and the bad.
Good luck! Often it's just a lot simpler not to ask, and go for one whose website you like the colour of the best.
One over-riding piece of advice - don't lock yourself into a contract longer than the bare minimum. Lots offer 6 months, most want you there for a year or two, and won't even disclose that they have shorter contracts. With a short one at least you can ditch earlier.