Many years ago staying in the US after getting a visa here was quite a challenge for Canadians and for other international students. I do not think that things have gotten any better. I recently heard of a couple of engineers moving from California to Canada when their temporary US work visas expired.
What will the master’s degree cost you in the US or in the UK? It seems that you might save buckets of money going to Toronto, Waterloo, UBC, or somewhere else in Canada instead.
At a minimum I would ask the departments at the US schools whether their Canadian graduates have been able to find work and get visas in the US.