US 23 is a 4 lane limited access highway. The only reason it isn't an interstate is because it doesn't leave Michigan. My preference (and I have driven to Michigan many many times) is to take the first route however. US 23 will take you around Ann Arbor, which could get ugly depending on what time you get there (you DO NOT want to be near Ann Arbor during rush hour). If you take I-69 North from I-80 (Indiana Toll Road) you won't hit a city bigger than Battle Creek in MI. Don't forget, the Speed Limit in MI is 70 and everyone pretty much does 85!
Oh yeah, another tip from someone who has been there before: Watch out in OH, most of the Highway Patrol units run laser. (That's how I got my first ticket years ago.) If you see something peeking out over the top of the center divider where it splits, assume it is a lightbar until you can confirm otherwise. They love to sit in the nooks and crannies of the concrete center divider. They are especially fond of cars w/o OH tags on the front. PA Troopers use K band almost without fail, so pay heed on K in PA. I don't want to have to examine any speeding tickets when I get to K'zoo.
