You bring up a valid point, but for the overwhelming majority (over 200 million customers), AT&T/VZW do provide the best service. Their network is expansive and their service is reliable.
I go all over the Northeast. The only place where T-Mobile service rivals AT&T/VZW is NYC and that's it. Even with their super dense network there... you still see instances where the big two are on LTE and TMo is on EDGE.
Well, I'm happy with T-Mobile, at least for now. I've only had two dropped calls in the past 7 months. With Verizon, I usually had 2-4 dropped calls every month. I enjoyed the seamless transition when I traveled to 3 European countries last month. Landing in Frankfurt and being connected to the Telekom.de (T-Mobile parent company) network a few seconds after the tires hit the runway (forgot airplane mode
I'm not saying that everyone's experience with T-Mobile will be as good as mine. I'm just saying a lot of things could still be better with all of the wireless carriers in this country.