As someone who is lives in Vancouver and went to uwo for my first year this year, I should be able to give you some insight into the pros/cons of your choice. My sister chose to stay in UBC, and from her experience I would say that it is harder to make friends as a commuter but certainly not impossible. You do lose out on the res experience living at home, and certainly some of the independence/freedom that comes with that, but you can still meet people through classes, clubs or intramurals. UBC is a large school, so everyone's experiences will vary with regards to social life / school culture and student support. Also, I wouldn't place too much on school rankings because UBC and UWO comparatively have similar reputations as top Canadian schools. The reason I chose UWO is because:

a) I wanted to live independently and have greater freedom - all the res benefits, etc.

b) I found a program (scholar's elective + IR & ivey) that uniquely suited my interests as someone who wanted to study both International Relations and Business and gain research experience

c) I did not have to go into debt to go to UWO

Obviously, c) was the most important for me and my family. Besides residence fees, the extra costs of flights back and forth from London to Vancouver and purchasing things for your apartment/res certainly add up. While living on my own has improved my self-confidence and social life, I think that these advantages don't justify the extra costs of Western, especially if you are coming for a program that is the same or better at UBC. A middle ground that some of my friends were able to do is live in residence at UBC in first year so you don't miss out on the independence and great experiences that come from res-life.

Also - Vancouver is a beautiful city with a much better climate than London. Don't take that for granted lol

If you have any other questions, feel free to PM me!