There's a lot of courts in the city and the good ones are typically very busy on good weather days. Today the weather was too humid so i'm not surprised you did not see anyone. I'm glad there's been a rise in indoor basektball courts and programs because if you're an old timer like myself and remember back in the day you'd be very hard pressed to find anything indoors recreationally unless you were seriously involved with basketball. Typically guys would play at outdoor school courts back then.
https://www.courtsoftheworld.com/canada/toronto/The main outdoor courts that i've seen are the following: I'm sure there's more if you're in and around the GTA you can add on to the list.
- Harbourfront - Downtown - i would probably say this, David Crombie and Christie Pits are the top courts in the city for finding good runs.
- David Crombie Park - Downtown
- Christie Pits - Downtown West
- Stanley Park - Downtown West
- Dufferin Grove Park - West End
- Underpass Park - Downtown East
- Jack Goodland Park - East End
- Dixon Park - Vince Carter Courts - West End
- Paul Coffey Park - Malton