Good write up! I use Sprint for the family plan for our smart phones (3 Samsung S4's and one iPhone 5) mainly because they have unlimited data, and monthly plan cost is less than either AT&T or Verizon.
Sprint built their coverage around interstates, main roads, and cities, and they are rapidly building out 4G LTE (they are behind due to their failed Wimax 4G initiative), so most of the time data coverage is fine. Sprint also roams on the Verizon network, so I have never been in a place where I couldn't get voice service. Data service while roaming is another issue, since Verizon pushes Sprint roaming users down to 1xRTT, which is painfully slow.
I also have a Pantech mifi hotspot on the Verizon network, which gives me 5GB/mo for $50. Even in the remotest areas, you'll still get 3G on Verizon in the unlikely case 4G is not there yet. When using the Verizon hotspot, I can link the smart phones to it via wifi so no loss of utility there.
Just wanted to add another perspective.