I live in Canada, but I watch Big Brother from the US, the UK and Australia.
BB Australia is definitely the best of the three. Big Brother himself has a hilarous sense of humour and a strong fist.
Not allowing discussions about nominations changes the show entirely. No more alliances, people survive the show based on their own merits.
Allowing the public to make the final decision of which nominated houseguest is evicted is definitely the way to go also.
The UK version has these same rules and is a very close second, but Australia wins because of Big Brother's personality.
Sorry, but the US version does not even come close.