Please rank these countries in order of which is the best one to live in - Canada , Australia , New Zealand , Ireland and Japan.?

That depends on the individual. But I will point out that all of those places have guaranteed healthcare for everyone and better benefits for workers than the US. Ireland is too cold and rainy for me, most of Canada is too cold (although I would happily live in Vancouver), Australia and New Zealand sound great, but they're SOOOOOOO far away from everything else, and I like to travel. Japan is very easy to live in- I could probably do that. However, I probably would have moved to Mexico if I didn't have family in the US. It's beautiful, warm, good healthcare, lovely people. 

the citizens of each will rank their own country at the top