There is really nothing else that compares to Canada's Wonderland anywhere remotely close to the GTA or Southern Ontario for that matter. If you want to get on rides you can opt for the occasional midway carnaval that pops up across the GTA or the CNE, both of which are just carnival rides and most often lacklustre overall.
The rides at Canada's wonderland range from simple carousel to high-flying roller coasters. There is literally something for everyone. Don't expect gourmet food but also know that there is no other place nearby that offers funnel cakes!
Admission includes access to the waterpark "splash works" and it isn't half bad. Outdoor wave pool anyone? :)