AT&T Next or the 2 year contract?

I'm a new customer and am planning to buy the Iphone 5C 16 GB. I will be the only person on the account/line. What would be the differences with the two plans? I heard that the Next plan (which if I get that plan if would be the 18 month one) gives you 10 GB for $100. Is it required to get that 10 GB because I really don't believe that I, only one person, would be using that much (probably only like 2 GB). I'm also hoping to get unlimited talk/text plan as well. I really don't know which plan (Next or the contract) to choose and which would be better for me. Any helpful answers would be appreciated!

AT&T next you are paying the full price for the device every month while the 2year contract all the devices are at discounted prices that's if you don't mind being stuck into a contract for that long