Hi Showe22 - last year and the year before I did a bunch of reviews of Ontario fields:
Outdoor fields:
Devil Dog
http://www.airsoftcanada.com/showthread.php?t=183337
Clarington Woods
http://www.airsoftcanada.com/showthread.php?t=183559
Niagara Quartermaster
http://www.airsoftcanada.com/showthread.php?t=183693
Ultimate Paintball
http://www.airsoftcanada.com/showthread.php?t=183788
Combat Pursuit
http://www.airsoftcanada.com/showthread.php?t=183922
Wasaga Beach Paintball Adventure
http://www.airsoftcanada.com/showthread.php?t=184561
The two major indoor fields in Toronto are:
Siege Airsoft
http://www.siegeairsoft.com/
Ultimate Airsoft CQB
https://ultimateairsoft.ca/
Mentioned by others above:
Finch Field
https://www.facebook.com/FINCHFIELDONTARIO/
Flag Raiders:
https://flagraiders.com/
I haven't had an opportunity to get out to Finch, so I haven't written a review.
To the best of my knowledge, Flag Raiders is closest to you (~24km), followed by Ultimate Paintball (~34km), Finch Field is almost equidistant at 34km Devil Dog is next (57km), NQ would be ~94km.
I think there's another field down in that neck of the woods, but I can't remember the name. I'll try to dig it up.