Queen's and McGill are both VERY LOVELY unis, in terms of atmosphere, location, and a few other considerations.
However, Queen's is UNDENIABLY superior to McGill for business programs.
As someone who lives and goes to school in Canada (Year 11), I have attended many university fairs and talked to many schoolmates going into business (my school won 1st place at DECA internationals [Business Law and Ethics if anyone's interested], so we are a high-achieving, business-minded lot
).
The consensus is this: there are two places worth considering if you're seriously interested in going to a good business program and want to achieve in a career afterwards...
Queen's and York University's Schulich School of Business.
I have nothing against McGill, I think it's a wonderful uni, but in terms of academia and ranking of the program, Queen's for sure.
To end: I have a close friend who will be going into Queen's commerce this September (accepted). If you have any specific questions for a prospective undergrad, I can definitely ask her!
ETA: Some more information on the other side, McGill...
McGill's BCom prospectus notes that 35% of its student body is international, 40% quebec, and 25% rest of canada. They also have an international summer program:
http://www.mcgill.ca/desautels/international-summer/