Originally Posted by number_6
Check the coverage maps. T-Mobile is the service I use, and it has good coverage in parts of the US, but terrible in some areas (mostly outside of big cities, but they had no coverage in Manhattan until about 4 years ago, and there are still some surprising holes in their service area). I think Verizon is available in more smaller towns. Where both have coverage, generally T-Mobile is better. So it boils down to what geographical areas you need the phone for.
T-Mobile used to be Voicestream which (in NYC) used to be Omnipoint. They had fine NYC coverage. I'm not sure what you're referring to here, but in any event it's ancient history telecom wise.
T-Mobile is pretty good in populated areas. On a pre-pay plan, if you buy a $100 top-up card the funds do not expire for one year. Otherwise I think you only have 90 days to top up again. If your phone does not do 850mhz GSM then Cingular is not for you as the coverage will be terrible.