You can argue phone, company, pricing, customer service, network speeds, reliability all that jazz. The bottom line is if you are a customer of a service you are happy with and it meets or exceeds your needs that's the company you need to be with. It doesn't mean it's the best company for everyone. I know a lot of happy AT&T users, but I would never use them again, not because of their coverage or their pricing but because of my experience with them and your mileage may vary. I know too many people who jumped ship from various providers just so they could get an iPhone. And while they love their iPhone and what it can do all they do is complain about the amount of dropped calls they have. Not smart in my opinion I would rather have a not so popular phone with excellent service, which I think most of us can agree on.
Speaking about the WiMAX "4G" it should give incredible speeds to the people who will actually benefit on their city list, and as the network grows so will the people on Sprint who actually get to use it. However I can't wait for Verizon to start offering their LTE "4G" which supposedly is what some CEO's think 80% of the cell network will end up being. Meaning the carriers that use it have a higher probabilty of having larger coverage as I'm sure network deals will be made to hand off to another carriers tower instead of roaming with no data coverage. I think in the coming years most carriers will be pretty much equal as deals are made and networks get rolled out. Think about how bad your service was just 5 years ago versus today!
The advantage to WiMAX is it's an open standard making the equipment cheaper on the customer and service providers end possibly making the phones and or service cheaper in the long run. But then you start falling back into the "who has the best network", "less dropped calls", "faster speeds", "cheaper bills", "I pay for the network" arguments.
In my opinion the phone does not sell me on the provider I choose, neither does the price of my plan or the speed of the internet on that provider. The coverage of the provider, and my experience with them is what sells me. In your area Sprint may offer the best coverage, in another it may be AT&T, in my area it's Verizon. Being able to make a phone call far out weighs anything else my provider can offer.
If everyone carried the same phones and had the same coverage that's when you could start arguing prices and customer service. This site is a pretty good indicator of how good the coverage is in your area, obviously the content can't be completely trusted as cell providers add new tower and better tech, but over all give a good impression of how things are different from area to area.
Cellular Coverage Maps of Wireless Carriers
I think everyone should be happy there are people out there that use different networks, and that different networks carry different phones it breeds innovation and competitive spirit. That's what give us these new network like WiMAX and LTE and give us such incredible phones from HTC, Motorola, Apple and all the other players. This is just the beginning of the game, I would just like to see all the cell companies come to an open adoption of service and have no more CDMA versus GSM etc. I think they should create a new cell standard where you can carry your phone to any provider. That way the only debate would end up being who has the cheapest price on the phone I like and who has given me the best experience!