The "sound king" brand at parts express has a good reputation.
I strongly suggest you go with 12 ga everwhere. You can go thinner for short runs, but it's kind of a pain.
If you go in-wall, look for the CL3 rated stuff made by "Carol". I dont know about Canada, but we have a lot of local laws and insurance companies that ask for fire-resistant sheaths on anything going in the walls.