My wife and I have been with AT&T for many years. We started in 2000 with Cellular One, and were bought by Cingular shortly after. We left Cingular for AT&T Wireless in 2003, only to be bought by Cingular two months later. In 2005, we renewed our contracts with Cingular, and were then bought by "the new AT&T." I upgraded my phone last year and got us on another 2 year contract. Our contract will be up in January next year. My wife doesn't like AT&T. She had a lot of problems with the network and her phones, but that seems to be fixed. As far as I can tell, the network works well enough for me. My company issued me a Verizon RAZR, and I can't tell a difference in service between that and my unlocked GSM Pocket PC phone on AT&T's network.
When I look at prices from the other companies, I'm honestly not inspired. Even T-Mobile doesn't seem that impressive price wise. Verizon and Sprint use a proprietary architecture which is on the way out in some countries, although our telecom giants have enough clout here that I see it remaining for a long time.
I would love to see some true competition and innovation in our telecom industry.