USyd and ANU have very similar, if not almost identical curricula.
The clinical teaching facilities in ANU used to be the 'Canberra Clinical School' of USyd in the 90s, and USyd was involved in developing the graduate medical programme at ANU (sorry but no references here - this is what I was told by Prof Ann Sefton who was behind the introduction of USyd GMP in 97').
ANU GMP is a new programme which will only graduate its first cohort next year. So in this regard you might expect USyd to have ironed out more creases in various aspects, but I guess this is difficult to ascertain unless somebody actually attended both programmes.
Wollongong GMP is newer still, and has a larger emphasis on rural medicine, with selection criteria that favours those who demonstrate an interest in this area (paraphrased from the W'gong GMP website).
Perhaps you should base your decision on the selection criteria (such as minimum GAMSAT scores needed, the relative weighting of GAMSAT vs interview score vs grades from undergrad). For example, USyd selection process is such that once you reach the interview stage, your GAMSAT score does not matter (unless you receive an indeterminate interview score, in which case they will go back to the GAMSAT score to fill the admission quota), whereas in UMelb they combine your interview score and the GAMSAT score for the final decision (but this is back when I was applying and things may have changed, so check on the application booklet that should have come with your results).
Good luck,
)
