Yeah Verizon is greedy, but where I am they are the best in coverage. Southern California, by the way.
Out here, T-Mobile is the worst in terms of coverage, followed by Sprint in 3rd and AT&T in 2nd. They're pretty much all bad, except Verizon. When my iPhone's antenna decides to act right, I rarely get 1x, normally get 2 bars wherever I go, as long as it isn't to far of the grid.
AT&T is really only good by the freeways and in the newer side of town. I don't know anyone who has Sprint, but I hear that it isn't the greatest in my area. T-Mobile is absolutely terrible. A friend has them because they are cheap and offer free international calls, but says the coverage is terrible unless they goes into Los Angeles or near the beach. They do get 4G, but no LTE.