I am switching from AT&T and I would like a phone that doesn’t require a data plan on one of the above carriers. Any suggestions?
Since you didn't specify any desired features, here are some suggestions:
Verizon: LG Cosmos (4 stars on the Verizon website) and Samsung Intensity (3 stars) both have 1.3MP cameras and QWERTY keyboards. If you don't mind the price, Samsung Convoy has a 2.0MP camera and Push-to-Talk features.
Sprint: LG Rumor Touch (4.5 stars), Samsung Restore (eco-friendly, music player)
T-Mobile: Samsung Gravity 2 (2.0MP camera, QWERTY)
Also, you can get selected phones from T-Mobile and Verizon at Amazon Wireless for a penny with a new contract!