AT&T, Verizon and Sprint iPhone 4S plans: Which is cheapest?

NEW YORK (CNNMoney) — If you’re getting the new iPhone 4S, you now have three options for wireless service: AT&T, Verizon and Sprint. unfortunately, there’s no app for choosing the right plan. If you use just a little bit of data each month, you’ll probably save money by picking AT&T. If you use a typical …