Sprint technically is the cheapest and might be worth a try, but they definitely lag behind the other carriers in coverage and speeds — though coverage is improved since they allow users to roam (with no limits) on T-Mobile.

T-Mobile is the next best in terms of price and is tied with Verizon as the fastest and their coverage is pretty close, at this point — though you will see more issues with coverage in buildings. One important thing to remember, T-Mobile plans include taxes and fees — so to correctly compare you need to add (depending on area) up to 20% to the price quoted to see what your actual bill will be.

One of the big issues is going to be coverage and there is no good answer. All of the networks have areas where they have coverage issues, the trick is to find the carrier that works the best for where you and your family use your phones.