The simple answer is that, while you can choose to take roads up that are toll free, that unless you go very far out of your way to use a land crossing that doesn't cross a river, you cannot avoid paying a bridge toll. The least absurd detour would involve driving north to philadelphia diet doctor Montreal, and the west south west from Montreal to Toronto. Which would increase your distance driven by about 40%.
So pay the bridge toll on the most efficient route and deal with it.
The least toll route northwards from Philly would be to take Route 309 north to Allentown, Take I-78 East to Route 33 north, then get on the 380 to Scranton, then I-81 North headed for NY state. From Binghamton, take Route 17/I-86 NW, then take I-390 to Sonyea, NY, to take Route 36 up to Alternate Rt 20 westwards, which becomes Rt 400 as it approaches Buffalo from the SE. From there, you can choose which toll bridge, you will use to cross into Ontario. But, they are all toll bridges, so there is no alternative to paying one of them.
Once you're on the Ontario side, the roads are toll free the rest of the way to Toronto.
