I don't know much about the master programs at these two schools, but I do know, based on the undergraduate program reputation, in Canada UWO' Ivey is considered the top 1 or 2 business school (the other school being Queen's Business School). UWO Ivey is very well known within Canada's financial center (which is Toronto), it is also one of the most popular schools to hire from, for anything from investment banking, to accounting...I actually have friends from both UWO and UBC, and UWO was way easier at getting jobs in Canada. But again, this is based on my understanding of their undergraduate school reputation, which may/may not apply to the masters programs.
Another thing to be aware of is, if it is your plan to stay in Canada for jobs afterwards, UWO Ivey is much closer to Toronto (Canada's financial center), as well as New York City and Boston, and Toronto firms in general have greater appetite to hire from Ivey compared to far-away schools like UBC (on the other hand, I would think UBC is a popular school to hire from in Vancouver - but the comparison of Toronto vs. Vancouver I would draw is, Toronto = Shanghai, Vancouver = Chengdu/Tianjin at best - so there is way more business job opportunities in Toronto)
Another example I can give you about UWO is that, like how a lot of business school in the US studies off business cases (class material) written by Harvard, schools here in Canada often will refer to business cases written by UWO Ivey.
So based on general reputation of the schools alone in Canada, I would recommend going with UWO. However, it does depend a lot on your goals after graduation (do you plan on staying in Canada or China?), if UBC's reputation in China is important to you, you should give UBS a thought. If you plan on staying in Canada afterwards, UWO Ivey is a great choice.
If it is your plan to go back to China, I would still encourage you to consider staying in Canada after graduation for some work experience here, which circles back to my recommendation about UWO Ivey....it is one thing to say you went to UBC (a school better known in China) for school, but it is another to say you work for this or that international company in Canada for few years, which is also well established in China.
Hope this helps. Let me know if you have any more questions, and let me know what you decide in the end.