Most Perth homeowners asking this question have a tile roof from the seventies or eighties and a quote in front of them for both options. The honest answer is that either can be right, and the decision usually comes down to four things.
Weight. Tile is heavy. On an older frame that has already moved, going to Colorbond takes a significant load off the structure. That is a genuine engineering benefit, not a sales line.
Maintenance. A tile roof needs its ridge capping re-bedded and re-pointed roughly every fifteen to twenty years in this climate. A Colorbond roof needs its fasteners and valleys checked instead. Neither is maintenance-free.
Heat and noise. Tile is quieter in rain and slower to give up heat at the end of a hot day. A properly sarked and insulated Colorbond roof closes most of that gap, but not all of it, and anyone who tells you it closes all of it is selling.
What your street allows. Heritage overlays around Fremantle and colour covenants in the northern estates both restrict what you can put up there. Check before you choose, not after.
If your tiles are sound and only the pointing has gone, the cheapest correct answer is often to re-bed and re-point and get another fifteen years. We will say so.