T-Mobile has constantly been coming out on top as of late, (in regards to customer relations/treatment) but they still don't quite have the network though, do they?
TMobile service is great in big cities. When I go home its 1g and Roaming(free). The real nice point is the great prices and excellent customer service. Today I called to see when my upgrade date is and I had a person on the phone and was done in 1 minute.
T-Mobile also has a policy of unlocking subsidized phones at the request of customers in good standing. 90 days? Paid your bills? Just call and ask. Done.
I've used t-mobile since they were called Voicestream. This was in New England, SW Florida, and now DC. Their network doesn't have the penetration of Verizon but I have never had any substantial issues with service. They even recently expanded to provide service in the DC Metro, which was a pleasant surprise.