Depends on where you live -- ask around and see what other people have and how they like their service coverage.

We are in metro Atlanta and have Verizon -- it is great. I would highly recommend it. In the past we have had AT&T, Cingular (now AT&T), T-Mobile and Verizon. Verizon is by far the best.

As far as the cheapest plan, most companies are pretty similar. If you go to someplace like Best Buy, they have a brochure that compares the cost of the different plans they offer.