I prefer cars I purchase to be made by workers who are treated well and paid decent amounts for the work they produce, if they are unionized, it's a big plus. I will not consider cars from companies who are doing union-busting, so Toyota and Honda, I will not consider your cars until you stop acting like Wal-Mart in relation to your employees in your North American plants (strangely, a disease that affects only their North American divisions, Toyota's and Honda's employees in Japan and Europe are unionized). Even Nissan's Mexican plant of Aguascalientes is unionized, why do you keep doing all you can to deny that right to your own workers in Canadian and American plants?
Besides that, I also prefer to support local industries over contributing to trade deficits, but I don't make much difference between Canada and the USA.