I have had Sprint for 10 years now can't go wrong with them! They are the best by far! My G/F's sprint phone will get service in the middle of Dale Hollow lake in tennessee now thats coverage. My phone is a smartphone and has great coverage as well. Forget the pretenders and go with the best Sprint if you can if not go with T-Mobile they are a company on the rise it seems!

three words. Virgin Mobil.

That's the same thing as Sprint as Virgin piggy backs on their network.

I have had Verizon, T-Mobile, and currently have AT&T (through StraightTalk).

So far I've been happy with all the providers and their coverage.

Now there is a company called Republic Wireless out of North Carolina. They offer an "Unlimited" plan for $20/month. When they say "Unlimited" they really do mean, "Unlimited." The way it works is that they use the Sprint network for standard data, texting, calling, etc, but when you are within range of a Wi-Fi, it automatically kicks you over to the Wi-Fi so you use as little of the network as possible, but they don't limit you at all from the Network. The company is new, but they are the real deal. Check them out:
http://www.republicwireless.com

AT&T and T-mobile basically share towers because they are the only two companies on a GSM Network (Verizon, Sprint, etc are all on CDMA Networks). Eventually AT&T and T-mobile will merge.

I've had to learn all the ins and outs of how all the carriers work from a method I've developed to bring high speed internet to remote racetracks in the hopes of one day returning to doing live video streaming.