We've had Verizon for many years and have had good luck in many areas out west. However,check every company's service area map. It is indeed true that along Interstates and larger cities there will be service but out in open country spotty...If the towns are small and far between you can bet service will be spotty. In our region most of the towers are Verizon towers and Viaero (Viaero has no sharing contract with other carriers). You will indeed run into dead zones
For example...we are near Crawford, NE...driving east from here to the nearest town to Wally World (30 miles)much of that route is a dead zone. Enroute to Scottsbluff to our south (70 miles) most of that is also dead. And that scenario is not unheard of in our region/areas I mentioned.
I'd not consider that a deal breaker. Good luck.
2002 Tiffin Phaeton
2005 Malibu Maxx toad