Not many snakes or bugs in Melbourne. You have to watch out for the spiders in Sydney, but I think there's another thread for that
Actually, it's not as good as it sounds. Looking at the article, they don't include cost-of-living in their decision process, and Melbourne/Sydney are getting expensive to live in. But on the criteria they use (healthcare, education, stability, culture, environment, and infrastructure), yes, Melbourne does pretty well. In my opinion, the perfect score Melbourne got for infrastructure is questionable, so I'm guessing they're only looking at inner-Melbourne. The public transport infrastructure in outer-Melbourne is fairly poor.