I would start out with some Veteran Click, Who Wride's self titled album is pretty dope, maybe some South Side Posse, and Vell Bakardy (despite a beef-inspired negative image around here) actually had a couple good releases. While not exactly "Kansas City" (or even technically the metropolitan area), I would say the Bombsquad too but they're from over in Lawrence.
Then there's some of the compilations from the area, like 50 MCs, Midwest Mobbin' and the Twinn City High Rollin' compilation which gives you a varied taste due to the multiple artists.
That's all older material though, not recent stuff.