Since 1970, Timeform Australia have rated them like this.
1 Kingston Town
2E Black Caviar
4 Better Loosen Up
5E Might And Power
5E So You Think
8E Lankan Rupee
10E Strawberry Road
10E Weekend Hustler
Geez I reckon there are a few glaring omissions there.
I'd have Octagonal, Lonhro and Northerly in my top 10 probably at the expense of Lankan Rupee (good horse he is surely he has to do a bit more), Hay List and Weekend Hussler (the EI champ).
Timeform make some dubious judgement calls IMHO.
Like when Weekend Hussler beat Racing To Win in a Ryder Stakes. They rated it one of the highest rated races ever - think it was in the top 3. I reckon with the benefit of hindsight, the race was run in the shadow of Equine Influnza, and it was one of the weakest runnings of the race.