Waterloo has arguably the best co-op programs of any school in Canada. This is especially true in engineering and computer science. If you are looking to transfer into Waterloo second year, a B average in first year university should suffice. They will put less pressure on you to attain higher grades because it's considerably more difficult than a high school curriculum. As for U of T vs. Ryerson, I'd go to Ryerson because their standards seem to be lower so you'd have an easier time getting higher grades, and Waterloo won't care whether you attended U of T or Ryerson, they will be more concerned about grades.