Only time I remember having no service at all was in the Hocking Hills, pretty sure even people on Verizon didn't have service. But if you're a country bumpkin pig fucker, then you should just stay on Verizon. Chances are you won't get 3G on T-Mo out in BFE. If you travel to other countries, you'll notice that you'll always have a working phone, Verizon not so much.
T-Mo just bought Metro PCS last month, so that will help grow their network and LTE.