AT&T (TDMA) and Verizon offer the best coverage.

T-Mobile is so-so as far as coverage, but I think they have a pretty good deal as far as minutes.

I just got my AT&T (GSM) phone yesterday and I love it.

BTW, I sell cell phones. I sell all the different carriers, so I'm not really biased any way. But, I can tell you Sprint is the worst, AT&T and Verizon probably the best. The only catch with Verizon is that they will always try to hook you with a 2 year contract. If they offer you a free phone, they're probably signing you up to a 2 year contract. If you make ANY CHANGES to your phone, plan, etc, they will restart your contract. Be careful!