I've had all three, and we currently have AT&T. If you have kids heading out of state for school, I'd say that AT&T is a plus because the family with unlimited calling within the plan is worth considering. AT&T coverage in the lower 48 seems pretty solid whenever we've travelled down South
My oldest son goes to college in Forest City, Iowa. NO AT&T coverage there! It's not a problem for voice, but becomes an issue with data. AT&T periodically threatens to cut him off when they notice that most of his data is out-of-network, so he tries to stay on wifi around campus as much as possible. We've looked at Verizon for him, but until they are up to speed in Alaska they don't work out for him either.
On the other hand my youngest son will attend school in Honolulu complete with AT&T 4g LTE coverage....so no problems to be foreseen there.
