OP lives in Los Angeles and T-mobile has a higher overall customer satisfaction rating from a consumer report's survey than does Cingular.
Actually if you look at the results of the survey (42,291 responses done 9/06) There is no city in the survey where Cingular finished ahead of T-mobile. They tied a couple of times (New York and Dallas) and there are a few markets that t-mobile doesn't compete in or they didn't get enough responses from (San Diego, Miami, Detroit and Cleveland)
The rest listed they beat Cingular and in some places they were the top overall (Atlanta, Boston, Chicago, Denver*, Houston*, Los Angeles, Minneapolis-St. Paul*, Philadelphia, Phoenix, San Francisco, Seattle*, St. Louis*, Tampa, and Washington D.C.)
* Were top in market or tied for top with Verizon (Houston, Minneapolis-St. Paul)