Square One Shopping Centre in Toronto has a dedicated nursing room that is good according to some nursing moms moms. It's built in 2015 and very spacious. There aren't many chairs for such a big room though, about 5 or 6 total.
When the door opens depending on which chair you're sitting in you are in direct sight line to anyone walking outside, so it's best to keep an active eye on the door to keep it closed while you nurse.
Square One's website stated the following: (Note: Many places often miscorrectly list their washrooms as nursing rooms. A washroom with a toilet is not a dedicated nursing room)
"Nursing Rooms and Family Washrooms are located throughout Square One. All of these washrooms are wheelchair accessible.
Level 2, across from H&M
Level 2, behind Michel’s Baguette
Level 1, within Food Central
Level 1, by Richtree Natural Markets
Note: Nursing in a public place (restaurant, mall, etc) is protected under the Ontario Human Rights Code. Moms can openly breastfeed without fear of harassment if they so choose