I've used AAISP for a number of years, primarily as a backup service for my satellite broadband because where I lived the phone was connected via damp string (or, that's what it felt like) and broadband speeds were diabolical. What I noticed there was that although it was a slow service, it never dropped out and never varied in speed.
I recently moved house to an area where Superfast Broadband was available and decided to stick with AAISP and I have no regrets from doing so. The service was connected when they said it would be and was as fast as they predicted (75Mbps - bliss!!).
AAISP may not be the cheapest supplier but from my perspective they are worth every penny of what you pay and I wouldn't hesitate to recommend them to anyone.