It depends on what you want to use the phone for such as voice or data, whether you will travel much outside of the US and what you are comfortable paying. I currently have TMobile and Verizon and in the past have had Nextel and ATT. I currently have a good friend who I travel with a fair bit for business as well as try to call who has ATT. With that experience base I can say I am quite happy with TMobile in comparison with ATT as far as service. I have had virtually no trouble using TMobile anywhere I travel. I dont, however, travel much outside of big cities or the Northeast corridor. He has huge problems with ATT. Most of the other people in our company who try to call him have Verizon or TMobile and we are always bugging him to get a new phone because we cant reach him and when he is with us he is borrowing our phones. He is too disorganized to do a number change though.

TMobile is cheaper than Verizon, especially in terms of data plans and has nicer phones with better features. On the other hand, when it comes to coverage, in my experience Verizon is clearly the benchmark. No one has coverage better than Verizon in the US. Tmobile is good, but it isnt Verizon. Thats why they cost more. How Cingular will impact this, I certainly dont know. If you are only interested in great voice coverage and a phone with good battery life for instance I would get a V60i for Verizon on Ebay or a new V60s through Verizon. Cant beat it for basic calling in the US. If you want more complex stuff look to TMobile.