The looping northern route may be quicker.
If you are going north of Lake Superior, you can choose the route that hugs the north shore of Lake Superior because it looks shorter than the looping route farther north, but I drove both by van in 2002 and I verified for myself that the route through Hearst and "Keep-us-cussing" is quicker than the shore-hugging route.
For scenery, follow the lake, but that will cost you a couple of hours.
Either way you go, you will pass through Ignace, ON. Try to do this at lunchtime, and stop at Captain Ron's for some delicious fish and chips. It's on the south side of the road, across from the IGA supermarket ... at least that is how it was in 2002.
Get a map from the government of Ontario, and study it. The little picnic tables denote rest areas, such as they are: some outhouses, some tables, and generally a stream that may or may not have water safe for drinking.
You will see little cairns made of stone atop every rock cut you pass through. Each of these is called an INUKSHUK and is a model of what you can find on some hilltops MUCH farther north, where one hilltop looks pretty much like another unless it is topped by one of these helpful sentinels. The temptation to stop and build another inukshuk is just about overwhelming. Succumb if you like; nobody will know unless you tell.
My trip starts and ends in Toronto, after visiting eight states and Vancouver BC, but I will go south of Superior both ways.