Best thing you can do is to find people that use different services.
Find out there satisfaction and also check to see how good the service is in the area that you need to worry about.
Verizon tries to sell my a package for an area that the coverage was lousy at best.
Tested out a Verizon phone of a co-worker and said no-way.
Preformed same tests with T-Mobile and Nextel.
No service is stable at the apartment, so why should I pay for something that will not work.