Well if you could go to the UCL and attend the Bartlett that would be amazing. Also TU Delft has a good program but it isn't such an exciting area.

UofT better than Waterloo or McGill?

There is no universe in the grand multiverse where that combination of possibilities exist. 

The program/school may have less of an influence on your work than what you're thinking right now. If you only go for ~4 months the pedagogy probably won't be too heavily driven into your academic pursuit. My biggest recommendation is to go to a country that isn't primarily English - the more difference from Canada the better. I think its also a totally valid opinion to look for a cheaper destination; Norway is wonderful if you're working (especially if you're working there) but very difficult to make work on a student budget!

I went on exchange to Finland during my studies (Im also Canadian) and took that time to explore the trans-continental culture of Scandinavia and its broader dynamic towards socialized societies and the resulting impact on its architecture and urbanism; I think it was certainly the best option for me. Other destinations were primarily western-European countries with large immigration to North American hundreds of years ago; Im not convinced you would find quite the same experience as going to London or Paris just because our own culture is so heavily derived from them.

I would recommend going somewhere where you can experience a different culture than your own. In my experience, this means somewhere where English isn't used as predominantly as Australia, Canada, etc. I would really look into the Czech program and Switzerland program. As much as I am for cultural immersion, I think for someone who may not be comfortable in places away from home, Singapore would be a huge culture shock. 

Through my studies I spent many months in Vienna, and a whole year in Germany, where I learned the language and was exposed to European culture. I am now working full time in Germany as an Architect. Your one semester study abroad experiences can turn into something a whole lot bigger, maybe even a lifestyle as a pond hopper. 

As far as the quality of the schools, I've heard good things about Prague's, and Sheffield as well. 

Thank-you everyone! I'm starting to think about things that I hadn't even considered before, this feedback is great.