Both the Westin and the Sheraton have been fantastic to me in Sydney over the past decade.
However numerous individuals stated the Sheraton on the Park became SPG unfriendly with regard to its elite upgrades. Based on a number of reliable sources I decided against the Sheraton and booked my stay at the Westin and was delighted in every regard.^

The Four Points has rooms facing a highway and a much less desirable location. I never understood why anyone would consider this property unless getting an unusually great deal.
The Four Points property in Sydney has gotten very aggressive with their pricing over the past few years as if it were a 4 or 5 star property.
In my own experience it is solid Three Star with nice service.

IMO its worth staying at the Wesin First The Sheraton second and the Four Points last place.As always experiences vary as do opinions