Based on the criteria you provided, I think most would be hard pressed to point to either as standing out from the other.
I know some Canadians that moved to Australlia and loved it, and some Australlians that moved to Canada and loved it.
If pressed for points either in favor or against, I would say that if you are a business owner, having the US close is a benefit, if you like to travel, there are more exotic destinations closer to Australlia.