Quite frankly, the best experience I've had in the, as well as friends that I know in the USA, is T-Mobile. They're easy to deal with because their plans are no-contract, the fee is what it is, besides taxes. Their nationwide coverage is pretty good, not perfect, but pretty good. I've never heard of a problem with T-Mobile and iPhones, but I have had intermittent issues with AT&T and Sprint.
