IMHO unless you are into gadgets or use lots of features, the phone is not nearly as important as the service. I live near the Catskill mountains. There are not a lot of cell towers in those mountains. Some services share towers, some don't.
My first service was Verizon Wireless. It gave pretty good service almost everywhere...except in my home or the mountains. I understand that Verizon only uses its own towers. The phone was a Motorola Star Tac (flip phone). It gave excellent service.
Next, until recently, we were on T-Mobile. It gave excellent service most places, except in the mountains. The phone was a Nokia and gave excellent service.
We are now with Cingular. It was an economic thing. My wife and I share a family plan with my son and his wife. It's cheaper. We get excellent service, including the mountains, so far. The phone is a Motorola 577. I have not had trouble with the side buttons yet, and now I will watch for that.
I would suggest looking up the service area maps online. Also check who they share towers with. Also check with your local friends to see who gets good service and who doesn't.
Good luck.
George