If you want to stay on the Canadian side of the US border, there is only one road across the MB-ON border (edit upon more investigation: only one that doesn't dead-end on the other side!), and that kinda limits your options.
Between Kenora and Thunder Bay, there is a northern route (17) and a southern route (11/71) with some north/south connecting roads between them but that's the basic choice. I don't know what you mean by "M-O-M's way".