G'day Peta,
Lots of good tyres out there. IMO best bang for your buck is Falken Azenis FK510. they outperform the stock Dunlops in every aspect. They are very good in the wet too which will help in the snow. They are considerably cheaper than other alternatives that offer the same or better performance.
I'm running Michelin Pilot Cup 4s and they are excellent. Expensive but the grip in dry or wet conditions is great, softer compound takes some of the harshness out of the stock suspension and they are quieter than the cheap chinese brand that were on the car when I bought it.