Straight Talk (walmart) works great... when it works. Heaven help you when you have a problem. We had it for a while, and even tho it was affordable, it wasn't worth the hassle.
We also only get ATT and Verizon where we live, and we got the TMobile prepaid phones. I have 1500 minutes or texts every month for $30 and my texting-teen gets unlimited texts for $15/month. I put $20/month on there so he can make "emergency calls" at $.10/minute.
We have never had a problem with them at all. I don't even come close to my 1500, and I'm not afraid to call my parents and chat or text either. My phone was around $20-25 at Walmart and it's a basic flip phone. My son's phone is a "smarter" phone that we got used at a pawn shop for about the same price. He likes that touch screen but I like the keypad with numbers!