Identify the best modem/routers for NBN users in Australia for the 4 speeds offered

Identify the best (by performance and price) modem/routers that will ensure that the speeds offered by telecommunication companies for NBN installations in Australia are not reduced by the modem/router. That is, one recommendation for 12/1, 25/5, 50/20 and 100/40. We hope the cost of the modem/routers will be less than AUD 100.