Is there any benefit to registering with the US, or would it be better to register with your own country outside the US?
Well, that would depend on where you think you will most likely run into copyright infringements and would want to litigate. In the US you would need to have a registered copyright in order to take legal action (sue a person) in a court of law. If your visitors are mainly from Canada and your content is more country specific it would be best to register in Canada. After that you can consider registering in the US as well.