If you are going to more than one place in Canada, Oneworld is not the complete solution as they have only international flights there.
I used the internal Canadian airline Westjet for flights within Canada. Also within the USA, American Airlines (part of Oneworld) does not always have the best connections - worth checking some of the other combinations of airlines on offer through agents.
Our international flights are a mixture of Oneworld and Star, and the cost was better than either.