All ISPs are bad and are over-provisioning. It just depends where you are and how bad it is.
It is also too easy for ISPs to shift the blame onto NBN considering the bad publicity it (deservingly) gets in the media. The whole rollout has been like dog's breakfast thanks to the politicians being politicians
Anyway, for example, Telstra may be better in one area but worse in the other. That explain why some are swearing by some ISPs while the others are swearing at the same ISPs. And it can all change from month to month as well.