Actually... while Sprint and T-Mobile have 1900 spectrum. Their liscenses are far larger/expansive than VZW or AT&T.
Both Sprint and T-Mobile have nationwide PCS licenses. They could build in Montana, Alaska, Nevada, Florida, Kentucky, Maine, Ohio, Nebraska... anywhere in the USA. They just have to get approval for a tower.
Where as VZW and AT&T can only build towers where they have spectrum (which isn't everywhere) and they use both 1900 and 850 (depending on location; sometimes both) and this costs more by using two different ''technologies''.
It also depends alot on where you live. In my town the choices are Sprint, Nextel or T-Mobile (CDMA, iDEN, GSM - respectively) and we don't even have at&t or VZW so your claims are null-void in our area.
To be quite honest at&t's 1900 service is better than their 850 service.. not sure why... my guess would be that it has less users on it due to the phones preferring 850 over 1900.
Most places it depends on location. In certain areas T-Mobile is better than VZW or at&t. In other areas at&t is better than T-Mobile and VZW. And yet in others VZW is better than at&t or T-Mobile. And still in other places Sprint trumps them all. So it all really depends on the location of the towers, geography in the specific area and the licensing which a carrier has.
T-Mobile. Connecting you when you need it most... disconnecting you when you need to connect with God's beautiful creation! Service is great in cities and highways, but in rural areas they leave you with just your surroundings. I encourage you to get T-Mobile, disconnect for a while!
I am glad that God is not like cell phone coverage. He does not hide behind mountains or loose us down long windy roads. The Lord levels mountains, and He makes our paths straight!