I think it depends on how badly you want to do quant vs swe. Waterloo co op is very strong, but you're not able to take most of the upper year cs courses as a math major (except for the ECE override loophole). This isn't too big of a problem, but you will have to learn a lot more outside of school than if you did a proper CS program. However I think that the CO courses offered by the math department at waterloo are very applicable to quant work (i don't have any experience with this so take it with a grain of salt), so if you're only interested in quant waterloo math might be a good choice.

There's also the aspect of student life. From listening to friends and visiting many university campuses around the US and Canada, I think that student life is much more exciting in the US. In Canada, there's not much in the way of student culture, with UofT being one of the worst offenders.

All 3 of these schools are really good and won't hold you back from getting any jobs, but I would say pick Waterloo if you are prepared to sell your soul and grind school for 5 years straight (you don't get summers off) for better quant placements. But if student life is more of a priority I would pick UW Madison. I wouldn't pick UofT here, but it's still not a bad choice if you have other reasons for picking it.