Which is the best country to study Masters in engineering management among USA, Canada and Australia?

Well, answer is USA for most. however, you need to see various factors. eg- if you are looking for PR later then canada and australia. if you are looking at high ranking big universities USA and canada. if your scores are not very high and extra curicular is not too good then Australia. if both are

in USA Sanford univ, MIT, Harvard univ, CIT are best In canada- univ of Toronto,university of British Columbia, Alberta univ are best! you better go with these two countries!

USA is the best.

there are different answers appropriate to your option but seeing all the factors existing us is good choice you can also get the opportunity for doing research after completion of your Masters so in all usa is good choice