Freshly renovated (since January 2019), the Dentistry Library, although a little walk away from the St. George Campus, is a colourful and modern library. It is a very nice library to study, with two distinct rooms with different atmospheres. You will have facility spotting dentistry students as they are all in their scrubs. If ever you are in core downtown, and are looking for a quiet spot to study, head there. And yes, the UofT wifi is accessible.
Far from campus.
* The rating, out of 5, is subjective based on criteria such as variety of study spots, outlets, aesthetic of the space, etc.