I had Sprint for 3 years, my dad has had Nextel for at least 5. If it weren't a company phone that he had to carry, he would chuck the thing in a lake. In town it works great, and the Motorola phones are nice, but reception anywhere outside of a metro area is LOUSY. He travels up and down I-95 for work a lot, and if he's more than 2 miles to one side of the highway or the other, he gets NO reception.
I was fairly happy with my Sprint service and reception, and the clarity was definately great, but I didn't get great service in the mountains and more remote areas. We were in Montana and Wyoming this summer and anyone that had cell service was using Verizon. When my contract expired, I went with Verizon. The service area is much greater and I get reception in a lot more places, but the call clarity sucks and I drop calls from time to time which never happened with Sprint.
With all that said, I will probably go back to sprint when this contract expires unless the clarity of Verizon improves. HTH
Ary