Which plan is better for buying an iPhone?

Verizon, Sprint, T-Mobile, or AT&T?
I'm looking for something cheap, lower than 70$ a month w/ unlimited text, and data?
I call but not that much

Added (1). Sorry if i sound vague? This is my first phone so if i get it i need to know the right plan for me!

You can actually get a plan on Virgin Mobile which is $30 a month and it piggy-backs off of Sprints towers. Otherwise Sprint will probably be your cheapest option, an actually contract plan will cost MUCH more than a Virgin Mobile plan.