Nextel in NYC and surrounding is pretty good, but they are expensive if you don't know anyone with other nextels since you can't use the "radio" feature. Plus their phones are expensive (but nice, new i95 is cool) and rebates aren't as good as some providers.
Att plain sucks in a lot of areas including dropped calls, poor signal strength, etc. But my plan is essentially free and so is the phone so i'll use it.