I can't personally vouch for any Canadian companies but i found this website which ranks Canadian seo companies, and they give quite a bit of detail about each:
https://www.topseos.com/ca/best-seo-companies-in-canada
Topseos.com gets quite a bit of traffic so I "think" that list must be somewhat legit.
I also came across this company before, which is pretty active on twitter and their website gets a lot of traffic too:
https://www.nirvanacanada.com |
https://twitter.com/NirvanaCanada
I'm sure others will be able to make personal recommendations but I would suggest seeing how much traffic they get themselves. If they can't get good traffic to their own website, then they're probably not a good option.
Perhaps you know all this already but if there's anything I've learned about SEO it's that content is the most important thing, and copyscape.com is a great tool to make sure you content is 100% original.