New Zealand!

But seriously....look at 2000 there was enough snow for everyone at all the resorts. Then again in 99 they were all asking the questions...what is snow??, what did it look like again???
Perisher and for that matter Thredbo would probably have good cover by then, If its a good season Selwyn Snowfields would be perfect for beginners as well.
They all have excellent snowmaking just to be on the safe side.
As far as Victoria goes. They all have should have enough snow by then, however as a rule of thumb Mt Hotham generally has twice the amount of Buller.
As for weather it can vary from +10 and sunny down to say -5 and snowing. Very rarely does the temperature get any lower than that in Australian resorts during the day.
As to which resort is the best one for you....I think its personal choice really. All are unique and all have their own pluses and minuses.
Cheers
Dr Snow.