Verizon
Had Verizon for the past three years (I use about 400-500 minutes/month). Service now is great, but it goes in fits and spurts; everytime they run a special deal and get a bunch of new customers, I start getting more and more dropped calls. usually improves within 6 months or so. I know its different all over the country, this is just the Utah market.
Also--watch the service plan CLOSELY regarding roaming charges. I took the phone with me to Chicago last spring and made 4 calls which ended up costing me almost $70.00!
My wife has had Voicestream for the past 5 years. Decent service, but in our state it does not work outside of the Salt lake valley (south of Nephi, west of Tooele, East of Park City). However, no roaming when she occaisionally goes to Denver. With them, Id check for service where you want to use them.
Also--I had AT&T prior to Verizon and it was the best service of all three, though by far the most expensive also.
Fly Safe!
PA