As someone who has been playing NSWGC since I was 14 and have as many non-architectural and sentimental fondnesses as it's possible to have for the place, I don't see an argument you can make for it being top three in the country.
The first two holes are lacklustre and appalling, respectively, the drive at the 3rd has become horrifically overgrown, the 6th is the Paris Hilton of golf holes, the waste areas are so choked with pigface and other plants they may as well be ponds in some cases, the drive at 15th is tighter every time I play there, deterring even low-handicappers from hitting driver and the new 18th hole is an insult to the rest of the golf course.
The fact the best holes are so good as to nevertheless get it into that top handful in Australia discussion is a testament to how fantastic those holes are.
It very well may be second 10 in Australia in its current state.
It very well may no longer be the best golf course in Sydney.