There was a recent thread about going from Rochester to Duluth, and how to bypass St Paul. Using the beltways doesn't add much time or distance, though.
I'm not sure why GM ascribes less time to the I94 route, even though the distance is longer.
I've driven both, and consider it a toss up, especially if coming from Wisconsin before the 2 freeways split up. I90 across southern Minnesota is supposed be bouncy (tilted slabs), but I94 has the Twin Cities. I94 has Teddy Roosevelt NP, but I90 has the Black Hills. I90 also skirts the Big Horn Mtns.
When I first drove west on I90 (with a small boat in tow) I crossed those mtns (on US14), into Yellowstone, spending the whole of 6 hrs seeing the sights, and continued on to Livingston and I90 west bound. But the return leg of that trip I took I94, and passed through the Twin Cities in the early morning hours.