It looks like you are wishing to purchase a new device with a new carrier! I have created a search results page of all of your available options when purchasing that iPhone and all of the available plans!
Remember choosing different ways to pay such as through monthly installments, early upgrade or lease will make that expensive upfront cost affordably split into a 24-month payment plan!
Now, from that results page, I have also created a list of the carriers that might be beneficial to you.
From these results, you will be able to compare data inclusions, minutes/messages and prices to choose the best option for you.