The southern route could be classed as more scenic depending on taste.
When you travel from Thunder Bay to Sault St Marie, you travel beside the lake most of the way. There are a few pretty towns. Montreal hill area has been compared to Califonia and looking out over the ocean. It is the best lookout area on the route but I see no comparison to California, LOl.
it is a different ride to the northern route. We prefer the northern route but that is because we prefer to be a little more remote and would actually take a logging road south instead of either highway.