If you are looking at POTS, then the last time I looked they were about the same price. A buck or two either way. Don't be fooled by the price for the 1st 3 months.
If you use a lot of long distance, then Shaw might be the cheapest.
And as Reaper mentions, VoIP is another option that is a lot cheaper. I have heard of mixed issues that somethimes makes it "Not Wife Friendly." (How long will you have VoIP if she burns up her cell minutes having you explain how to re-boot the router.)