The quality of the internet connection depends on many facorts. There are many websites, which provide comparisons on internert service poviders. Search on Google for internet comparison. Please, note that some comparison websites can be biased.
For ADSL, the most important factor is the distance from your home to the exchange, which the service provider uses.
If you ask your friends, who live at different areas, they will most likely give you conflicting information about service providers. For a certain provider, the quality of the service can be excllent at some areas, but very bad in other areas.
If I were you, I would ask my neighbours about their satisfaction of the internet service provider, which they use.
For NBN, it is bit more complicated than ADSL. Plese, refer to the following question for more information about NBN. I would still ask my neighbours abort their experience with different NBN providers.
https://newaussie.com.au/categories/utilities-elec-gas-water-tel/101-what-are-the-different-types-of-nbn-connections-available-and-how-can-i-know-which-one-is-better
Update in 2023:
- 5G provides excellent alternative to landline connections.
- Most dwellings (homes, apartments, etc) have some kind of NBN.
- I still suggest you ask your neighbours about their experience with the different services in your area.
