We have had Sprint, just doesn't get the best coverage were we are and I was never impressed with their customer service.
Right now I have AT&T, great service where I live and great customer care. I've been with them for over 7 years and have no complaints. I also have an iphone. Mine is $115.00, unlimted talk and text, 2 gb data
My husband is with Verizon, again no real complaints other then the phone we got him was crappy so we are waiting to upgrade him. My husband is on a friends plan, it was cheaper that way and there are 4 phones. 2 smartphones and 2 traditional phones. There is unlimited text and talk, and 2 gb data and the total is $180.00
My kids all have Boost Mobile, they don't get the best service were we live since it's a co-company of Sprint, but every where they go it is great. They pay 50.00 but they have raised their smartphones to 60.00. They also have it to were if you pay on time for six months they knock off $5. If you're good about it your bill can get as low as $35 a month.
They are all great, i have no complaints and none of us have every gone over our data plan because just about every where has wifi. It's really just a matter of picking one and going with it.
ETA..................................
My DD works at a Verizon call center, and yes unlimited is gone or going away. We already gave it up cause there is no real need for unlimited. As I said, just about everywhere has wifi. That is also Verizon's thinking also. Another thing with Verizon is they are phasing out 'traditional' phones, will most carriers are, and pushing smartphones. My DD also says that have the store personal don't know what they are talking about, and that leaves her in the unfortunate position of dealing with all of the angry and pissed customers.