Which cell phoe carrier is right for me?

I want to upgrade to the S4 from an iPhone but I'm sick of paying $100+ a month for AT&T. My contract expires soon and I want to switch carriers. The problem is, I just don't know which one. I want to spend about $70-$80 a month for unlimited text, doesn't matter how many minutes and at least 2GB of data. I like T-Mobile's pricing but I don't like the idea of paying $25 a month for the phone. I also don't want to spend $400+ to get the phone through lesser tier carriers. Any suggestions? Thanks.

Added (1). I saw I spelled the title wrong. Oh well.

None… You must decide to have a pricey phone contract with a huge discount on the phone, or a cheap monthly charge where you pay full price for your phone.