Hi Sky,
There's a few of these Aussie threads popping up, you're in good company.
The "best" index fund is a subjective thing. One way or another all track a market performance, and they are differentiated on fees, entry/exit costs and liquidity (how fast you can get your money out).
I'm a fan of the State Street SPDR funds which are listed on the ASX. The most well known is probably the ASX 200 fund (STW).
Other options include listed investment companies such as Australian Foundation or Argo.
Else you could buy the mum and dad portfolio. My parents figure that everyone eats, talks and banks, so they bought Woolworths, Telstra and CBA, ANZ and WBC shares. Cannot fault the logic given the returns of the past 2 decades.
cheers