I switched from TMo to ATT and never looked back. Save $199 and go to Wirefly.com or Amazon.com and get a great ATT phone for free. And the ATT unlimited data plan is only $15 while TMo is asking $20.
You don't know what you are talking about. Your "unlimited data plan" from ATT for $15 is the Media Net Unlimited which is only for dumbphones. ATT has their REAL Data Plans priced at $30 A LOT more expensive than T-Mobile's. T-Mobile's dumbphone data plan, T-Mobile Web, is only $5.99 a month A LOT cheaper than the $15 ATT asks for. So basically you're are getting ripped off. And btw you can get free phones from wirefly.com or amazon.com for any carrier, not just ATT.