As someone who pretty much never leaves the city, I'm very happy with T-Mobile. Unlimited everything for $70 a month. And there's no contract; I walked into the store, said "may I have a SIM and the unlimited everything plan", gave them a 4 digit number to use as a PIN, and walked out. I could hardly believe that this was happening to me in the United States, but hey.
Verizon may have slightly faster speeds and better coverage, but T-Mobile's user experience cannot be beat.