Not sure of your tyre size? This may affect availability of the tyres below.
Two options I'd suggest:
For us, we got over 100,000kms out of Yokohama Geolandar A/T-S on a Forester Diesel, and I didn't drive particularly gently on them either. They are an 'all-terrain' but quite passable on road. Lasted 2.5 times as long as the OEM tyres with only minimal on-road loss of performance and a huge dirt-road gain. Brilliant tyres overall, probably the best I've owned. Don't know if they are still available.
As you effectively say you're 100% on-road, perhaps look for a good quality touring-type tyre, and don't go cheap. A good quality touring-type tyre tends to be almost as good as a sport-type tyre in terms of grip, and quieter and longer-lasting to boot. I had Michelin Primacy 3ST on a Mazda 3 diesel and they lasted very well and the tractive grip on a diesel FWD is quite astonishing, it's limpet like, almost simulating having a LSD (and believe me, I tested them out). Cornering is OK and steering not up to 'sports tyre' levels of feedback, which is in keeping with a 'touring tyre.' The one drawback I will specifically mention (given you say you're based in Sydney) is, with relatively narrow siping they need to be replaced when they get to or near the wear limit markers as when worn they don't cope well with sudden Sydney downpours, specifically (say) a thunderstorm on the F3 at Buladelah (and yes I speak from experience). They are also a very quiet tyre and the Mazda 3s need 'em to be! I suspect they do reasonably well on fuel economy too. They are a several year old design and may no longer be available, superseded by the Primacy 4 ST (not evaluated...yet). If the 3 ST are available, check the build date- I was supplied tyres 4 years old booked through tyresales.com.au. If you do high mileage, this may not be an issue as you'll be through the tyres within a couple of years anyway.