Pros: Scenery, conditions, terrain
Chestnut counts as home, I've skied here for a long time. The area is one of the most scenic that I've enjoyed, with the Mississippi at the base. The conditions are good due to extensive snowmaking and an ample water supply (did I mention the Mississippi at the base!) The terrain has plenty to offer for a Midwest resort, the down side is that the runs are short.
Personally, I love Apache, it has a sweet double fall line most of the way down, which gives you ample room to play with gravity.
The newer developments are 2 new runs at the south end, Warpath has a nice steep pitch at the top, which is great when conditions are optimal. Crazy Horse sees more traffic and is shaded most of the day. The other new development is the Far Side terrain park, which is serviced by a single triple, but offers a mix up of terrain and features (for those so inclined) and a half pipe.
Given my other choices from the Chicago area, there really isn't any other choice that offers the pros of Chestnut!