Sports is a really easy way to meet new people, especially if you are moving to a new city/country. Toronto being a multi-cultured country facilitates all the major sports around the world.
Toronto is home to some of the big teams across North America. Maple Leaf sports entertainment (MLSE) has franchises for most of the major teams in Toronto except Toronto Blue Jays.
I have been to numerous Toronto FC and Baseball games. Trust me, they are extremely entertaining and worth your time and money.
Hockey has been the most popular sports in Toronto with the sport being played all year round. The popularity of soccer has been gradually rising because Toronto is home a large immigrant population from around the world. There are numerous recreational leagues Outdoors (in Summer) and Indoors (in Winters) that are played in Toronto.
Personally, I have been playing in soccer leagues since I moved here in 2012. For a new comer the Facebook page of Toronto Soccer Connection will be a good place to start knowing people.
Toronto also has cricket leagues and clubs located in different areas across GTA (Grater Toronto Area).