With that said there's no reason to pay more than you have to. Luckily wallethub.com has already done the math for us. It looks like the best plan is to go with the 2 year contract via Verizon and get the phone for "free". I say free, but you're actually just subsidizing it via your high cost phone plan. Regardless, it looks like it's the best one to go with. The part that makes it easier is that Verizon is also the best network in my opinion. I've had very few problems with it in the 4 years that I've been using them.
With that said, if you're willing to not go with an iPhone than you can get extraordinarily cheaper plans. Practically free phones with minimal contracts and decent features. I'm still considering going this route, but we'll see. My phone storage is maxed out and I "need" a new one. Oops, there's that word again...