I have been to both and here's what I can say:
MDW: Good airport, very clean, business center is nice, food court and security won't be bad because it's not an intl' airport.
MCI: Good airport also, but if you want to get business done during your stay, you will want to stay out because they are redoing the entire airport terminals. And it's a bitch to go from gate to gate, or from the gate to the bathroom.
In conclusion, if your not a big spotter, MCI has less traffic, hence you have better chance of getting to your destination on time.