Quick note -- if you're taking the GRE, then you're talking about grad school. For non-professional programs (i.e. non-engineering, non-medical, non-business), any decent school will give you complete funding: tuition waiver and a TA-ship. That's not aid, it's what comes from being in a good program. If you're being asked to pay the cost of grad school, that's a sign that your program is poor and you should avoid it. Sometimes the scholarships are contingent, but they exist.
Professional programs are different, I doubt what I wrote applies to them.
As for the original question, the reason many people study in Canada is that they like Canada and want to live here. It's a weird idea, that countries get ranked, and that anyone who goes to, say, Belgium, must be waiting for an opportunity to move to Germany. Does everyone from Karachi want to live in Lahore (or vice versa)? I'm an American who studied in Canada, here's why:
- I grew up in a crummy state -- once I leave the state to go to another American university, out of state tuition would be equal to or greater what I paid in Canada
- the good Canadian universities are equal to good American universities
- Canada is a better place to live than the United States
- it was easy to get a visa, simple to live here, and now, simple to immigrate
If I was an international student coming to Canada to study, I would have no qualms at all about any undergraduate or graduate degree program at any 'normal' university -- but I would look out for all of the certificate programs that schools are developing to suck in foreign student money. A certificate is not a degree, and in Canada, a college is not a university . . . I wouldn't assume that they are valued by employers.