It probably depends on what you're looking for, but I've bought from https://www.reliablerxpharmacy.com/ with great success, as have several of my friends. You can get a lot of stuff for super cheap and I've never had any kind of scam issues or payment discrepancies. I've only purchased generic Retin-A and careprost, to be honest (skincare and eyelash growth) which is completely irrelevant at this point in time and kind of embarrassing, but I've got great skin and super long eye-lashes now. Haha. Kind of vain and ridiculous, but they were definitely reliable.
Canadian online pharmacies can get approved by 3 different agencies. I would use one that has all three stamps of approval. I have used numerous different canadian online pharmacies with no problem, except they all claim the best prices which is not necessarily true. They do seem willing to price match though. Goodrx.com will steer you to best prices. That is locally and online. They have a pay for service dr online for common prescriptions but i have not used that service.
My father and his friends, some of whom are doctors, buy their drugs out of Canada. I forget the name of the group they buy from thought but it is certified by some group, which the doctors think highly of. From experience the Canadian group bought from has worked well, with low pricing, quality products, and delivery.