Well think of this. If you switch, you can talk the phone and browse the net at the same time lol. Ive been with AT&T for about a year now and I switched from Verizon. Not because of the network, but basically because GSM networks come out with Better phones. Unlike Sprint and Verizon, AT&T and T-Mobile have sim cards. You can take yours out and swap it in another gsm phone.
And the network is not bad at all. I never had a problem with the network. Calls are clear, Data is quick enough and everything is fine. I think the network issues are a thing of the past with AT&T. Its not crappy like it used to be a LONG time ago. Nowadays, there network is all over. In my areas I have been, I wouldnt say its any better or worse then when I had Verizon. Both were fine for me and performend about the same. Although with AT&T I can do voice and data. No go with Verizon or Sprint as there CDMA carriers.