MDW is the best for crashpads. Better than BWI. Because at MDW you can walk right across the street to crashpad land. It's 10-15 minutes from the terminal. At BWI, you can't walk to your crashpad (well, you could, but it would take 45 minutes or more). Either need a car, taxi, or have to ride the train. Waiting on the train takes time and obviously costs a few bucks.

Also, I'm pretty sure there are more pads in MDW to choose from.