eatersmeater
If you were merely wanting to rent and applied to get a conversion from the FAA based on your Canadian licence then you are not required to have a visa. The conversion however will only recognize private levels of flying.
If you wanted to get the full unrestricted FAA CPL and IR, you will be required to get a visa as you will need to complete training towards the licence/rating or certificate. Even is you only need to complete the FAA required 3 hours in the preceding 90 days, you need a visa.
The visa process is simple and painless; just go to the US Embassy web site and they will tell you what is involved.
Good luck