Generally speaking, I think York MBA is a little bit better than UBC. You can look at the rankings for your reference . And since York is in Toronto, it will be a little easier to find a job after you finish your MBA study. But if you are in Vancouver and do not want to leave there UBC is also a very good choice. BTW, the tuition fee for UBC is much lower than Youk, York's tuition fee soared in the past 2 years. From this point of view, I think UBC MBA ( or maybe McGill ) is the best value for money .
You can also refer to #18917 for the discussion of MBA in Canada.