97 has a lower speed limit than Hwy 8 and less hills than Safari. It allows a connection to Blair rd which has dedicated bike path, which in turn connects to other dedicated paths as it meets Homer Watson
Is there a reason for downtown TO? it's a bit indirect if Kitchener is the end game. If more about the ride than the location you may consider coming a fair bit further north, starting west at Hwy 9 and staying completely north of Brampton. Start going SW on old 24 through Erin on rural routes and taking yourself through Guelph instead.
The hills in Dundas are killer, but the trails are plenty.