B.A.C. Horn Doctor is the best in my book - both in the KC area and in the upper Midwest. They've provided quality instruments to me and clients as well as serviced many of our horns and we've never had an issue
BAC is top notch for skill, quality, and repair/customization options for instruments. Their new store space is spacious and clean, and the employees/technicians are knowledgeable and really great people (I used to work here).
Went in today thinking we would look at jazz model trombone for my son and ended up coming home with on that has made him VERY happy! Excellent customer service. Worked with us to get us the best deal that fit our budget.