What is the best prepaid carrier if I have an unlocked GSM IPhone 5?

Hey y'all! I have an unlocked IPhone 5 model A1428 (GSM). I'm interested in using prepaid carriers for the sake of long-term savings. Which prepaid carrier is the most reasonable considering monthly cost and coverage?

Assuming you are in the US Tmobile is the way to go they have very affordable plans with good coverage. Ask around in your area to make sure which carrier is best there.