26% Federal + 11.16% Provincial = 37.16% http://www.cra-arc.gc.ca/tx/ndvdls/fq/txrts-eng.html
San Francisco: 28% Federal + 9.3%x(0.72) State = 34.7% <-- (9.3%x0.72 because you can deduct your state taxed amount in certain scenarios)
http://www.efile.com/tax-rate/federal-income-tax-rates/ https://www.ftb.ca.gov/forms/catxrate_exmpt07.shtml
Once you get above 174k/year, it's sill similar, with:
Waterloo: 29% Federal + 11.16% Provincial = 40.16%
San Francisco: 33% Federal + 9.3%x(0.72) State = 39.7%
So at 100k, Canadian taxes are very slightly higher higher, and is almost even at 174k.
If you're working at a startup, Canada may even be more advantageous because of how capital gains taxes are treated on privately held CCPC's. Also, you have health care. :)