too hard to say which one is popular, it depends on which one suits your bub best.
For my daughter, she's using Huggies most of the time, especially the night time (i don't use other brand for night time, because this is the only one doesn't leak more than 10 hours.) However, I also buy some other brands nappies for her day time, such as babylove, or pampers when they are on special (sometimes it's up to 50%off, good deal!) I don't buy snuggles anymore, because even during the day, it leaks!
I know there are quite a lot mums buy homebrand and aldi, they told me, those brands are not bad, but personally, I don't like them because they are too thick.
For formula, S26 gold caused my daughter lots of problem at the beginning, then we changed to Novolac due to her reflux, she was so happy after, and her reflux was settled. However, she's now having NAN HA Gold, because it's easier to buy from lot of places.
As I know the formula I mentioned above, they are not made in Australia. But, I saw Aldi is selling mammia infant formula, it is made in Australia. If I am right, there is an organic infant formula brand (not sure the name) in Supermarket, it is made in Australia.