Another vote for .co especially if you don't want to limit yourself to Canadian market.
.CA sounds too Canadian. Although .co is also for ccTLD for Colombia but its perceived as "company" among most internet users.
Yes, they are specifically branding .CO as "worldwide"; I can't find the full nexus agreement right now, but the first time I read it, it was *very* brief (that's a good thing in terms of restrictions). .CA is alot harder to get, their nexus is much longer and they enforce it fairly aggressively.
Personally, I prefer .CO over .CA if I *had* to pick one. But once you're down the road of ccTLD's, it's worth looking at a bit more in-depth (and Yanks, remember, 90% of the .CA population is massed within a one-hour drive to your Northern border

)
So if someone has an opportunity to snag a harder-to-get country code TLD, I generally recommend getting it along with a few other extensions that are available.
Final thought - check with whatever registrar you're going through. Many registrars agree to lock in your renewals at the price you pay for the original registration for as long as your initial registration is.
So, in this example, I would grab the .CO for 3-6 years and the .CA for 2-4 years.
There may be SEO boosts to longer lifetimes on an initial reg over time, I've read and tested and talked with a number of people on both sides of the fence that I can't tell you my opinion any more I gave up worrying about it a long time ago.
Go Leafs!