I'm not a T-Mo fan, being here in the PNW with holes bigger than some of the smaller states in their coverage and plenty of mountains too. If I were you, however, in Kansas T-Mo would get a pretty good look from me along with Cricket Wireless. USCC and T-Mo signed a LTE Band 12 interop agreement last year with ATTWS, supplementing T-Mo's own LTE Band 12 buildout (
http://maps.spectrumgateway.com/t-mobile-700-mhz-spectrum.html). I'm spending time with my mom in rural WA, and my brother pops in from time to time - he's from Sitka, with GCI that roams on T-Mo's network in the Lower 48 and his two iPhones (work and personal) have had a pretty nice boost in reception since the roaming agreement kicked in; I know where the nearest ATTWS antenna array is as I helped install it years ago - I tell him where to stand and which leg to stand on to get a decent signal.
Check that Band 12 Map, and consider one of those T-Mo test drives - with a phone that has Band 12 built in - like the iPhone 6S line and not the 5S they were pawning off last year, or use your own compatible handset.
FWIW, I use a weBoost eqo with an external patch antenna too. These hills around here make reception a bit of a PITA…