Go to each providers store in your area. Once there grab their coverage map and plan rates. Go home and look over said articles and find the company with the most coverage at the lowest cost.
What works well for me might not for you. A great example is an older commercial from Verizon:
[ame="http://www.youtube.com/watch?v=VZPjJI0K7Bk"]Verizon Vs. AT&T - "There's a Map For That" Commercial - YouTube[/ame]
AT&T HATED that commercial and in fact tried to sue Verizon to have it removed. But the truth doesn't lie. Every carrier has a map of their "regular" coverage and their 3G/4G coverage and at the time the 3G coverage Verizon showed in that commercial was 100% true. It also explains why, at the company I work for, people in Cincinnati, OH loved their iPhones but the people down here in Lexington, KY HATED theirs. If you looked at AT&T's map at that time, Ohio had great regular and 3G coverage while Lexington had no 3G coverage and thus why our people down here kept dropping calls... and still do from time to time.
Just to put it in to prospective, Cincy and Lexington is only about an hour away so we're not talking great long distances here.
For what it's worth, I do have Verizon and have had them since high school. I've been with them since my first cell phone and have never left.
-Michael