Emergency only use, as in 911 type calls I don't think you need to pay for ANY plan. Buy a decent used cell phone with a car adapter, do a simple page on how to use it, and put it all in a bag in the glovebox, done. I am sure people will chime in with more details or corrections, but thats how it used to be.
Calling 911 from a cell have some real weaknesses, mostly no automatic they know where you are and that its not a prank call.
Very low use non 911 calling can be done via special carriers that charge $2 a min or so and want a credit card number.
Next is the Virgin Mobile stuff with the 90 day autocharge thing to keep it alive.
Any regular use, even just weekly stuff, and I think T Mobile edges out Virgin due to the first 10 min of each day costing 25 cents per min on Virgin. Incoming text messages are free on T Mobile and I plan to use that feature A LOT.
Seems to me all the fuss here is pointless, pre paid is CHEAP and easy to just walk away from if you don't like it.