T-Mobile has great customer service...their coverage is the pits, however. I had them when they were VoiceStream and loved the support, but the first time I REALLY NEEDED my cell phone in an emergency, I couldn’t make a call. My daughter and I were in a car wreck on the highway a couple of hundred miles from home and we couldn’t get a signal. Switched to Sprint after that. After 2 years of their nasty support, T-Mobile promised us they had better coverage than before. They do, but only a little bit.
My current contract runs out in a few months...I was going to go with AT&T, but not so sure after reading all of this. Maybe by that time, Verizon will have the iPhone and I’ll have my husband talked into springing for one. ;-)
Do your research and read some other reviews like on cnet and PC Mag, etc. Also Google for JD Power and look at their cell company ratings.
I also had VoiceStream until I went on business to Richmond VA and discovered VS had *no* coverege there at all (Richmond is the capitol of Virginia).
Switched back to Verizon with my old StarTac (I'd been with them before), and then hated it when I went abroad for a few months and had to rent a Vodaphone GSM setup for emergencies and business calls.
Came back and looked at U.S GSM providers, and since T-Mobile had lit up Richmond by that time (and other improvements) I went back to them and have stayed there since.
In 2005 I was again overseas and came very close to buying a GlobalStar sat phone. That's the best solution of all.