Well of course CBC has a bias. What else would you expect? Every media outlet has a bias. They're all run by ordinary human beings, who have biases, and opinions, and commercial interests they have to satisfy, and political interests they have to satisfy... There's no such thing as completely objective reporting, and there cannot be. There's a lot going on in the world, and the people running the mass media have to make decisions about what to report on, in how much detail, and of course the result will display their biases. That's why you can't rely on just one source, you have to sample a range of them. And if you don't, you're just displaying your own biases.
I routinely sample CBC, CTV, Global, Fox, CNN, my local newspaper, the Toronto Globe&Mail, Maclean's magazine, and Time magazine, most of them daily, or at least weekly for those sources that publish weekly, and a variety of others less frequently. It's often very interesting how the different outlets report on the same story.
And in defence of the CBC, I'd agree that it tends to be somewhat leftist, as these things are usually defined, but it regularly comes closer to pure objectivity than anybody else does. It's a very high quality source for news and information, one of the best in the world, and it deserves respect and support.