NBN is basically a lottery. Fibre to the home areas generally get a good consistent service but HFC, FTTC & FTTN areas can have a lot of issues. iiNet was bought out by TPG and their service gradually became worse after that, although they are probably still better than Telstra and Optus. Superloop/Exetel & Aussie Broadband are the better mid-sized ISPs these days in my opinion.