Best cellular carrier for camping?

[rjniles]

I am looking to save some money on my cell phone bill and at the same time get a larger data allowance. I am on a post paid AT&T plan with UTT (unlimited talk and text) and 6GB of data shared between my wife's and my phones. My coverage in the areas we camp is very good with AT&T. We mainly camp is SC, NC, GA and FL Have been to PA and TN a few times.

I am looking at pre-paid plans from Verizon (Visible) T-Mobile pre-paid and AT&T pre-paid. While I know the coverage is good with AT&T, my concern is will Verizon or T-Mobile be the same. T-Mobile has the most attractive plan (UTT and unlimited data for 2 phones, $55 including taxes and fees). But i have seen other reports that T-Mobile's coverage is less that optimum in rural areas.

What is your experience with these carriers while camping in the SE US?