Polar bears survive in artic climate, this would be a point for them. On the other hand they are in danger of extinction, this sounds uncool for the creature and for a nation, like adapting the dodo.
Beavers however have a reputation of being smart, plus a much longer cultural history with the First Nations - but beaver fever is no fun.
The moose would also fit as the national symbol, however it's already taken by the Swedish.
Sea lions would also be cool, however discriminating agains the Canadians who don't live at the coast; Seals on the other hand are not a wise choice unless the clubbing stops.
Canada could also try to take back the Bald Eagle from their pesky neighbors, there are more of them in Canada than in the US anyway.
After long and deep consideration, I'd go with the fox: it lives in all regions, it's definitely a survivor with enough willpowerq - and it would be a great way to spite Canada's former fox-hunting overlords - plus it also worked as a symbol for a well-known browser.
