If there is a difference between the vic and nsw npl it’s just part of the natural ebb and flow of leagues having stronger and weaker periods Ala the “big 4” in Europe imo. Dare say if you go back through the decades there would have been periods when the nsw state league was slightly stronger and periods when the vic state league was slightly stronge for various reasons. In saying that no idea how you go about quantifying this, take it with a massive pinch of salt imo. It’s like those economist magazine city livability rankings or time out magazines “coolest neighbourhood” rankings. Based off some random company’s subjective arbitrary criteria and then claiming to be an offical ranking