Fosters doesn't even exist in Australia any more as far as I know. I think the highest selling would be one of our Cold filtered Lagers, rather than one of the umpteen million IPAs available.
Aussies are turning into beer snobs like so many others, and frankly it does my head in.
Drink what you like, and one man's swill is another's nectar of the gods. The tosh about "best beer" is all BS, because it is 100% subjective, and some dickhead "beer" judge trying to tell me that this beer is better than that is crap.
From my personal point of view, I've met a few US beers that were OK, some Canuck ones that were GREAT, Czech, Belgian german, french, hell even dutch and italy can make the odd decent beer. Most English bitters and browns aren't really to my taste, so I wouldn't have a clue - they all taste like shit to me (yes even Guiness).
Best beer (to my taste) I've personally ever drunk is Stone & Wood Pacific Ale, but Ive had some mass produced that tasted really good at the time I drank them as well due to company, associated situational memories and so on.
Just cut the shit about "best" - its nonsense.