I was actually asking Nolegirl01, but assuming you both are on the same track, then lets compare apples to apples, because the 30GB 2-year contract price doesn't have the upfront cost of the phones factored in, nor the fact that on the 2 year contract, you're paying $40/mo per line for service, compared to $15/mo for NEXT. Calculate out 2 YEARS of total expenditure and you'll see on the 2 YR contract, you're spending about $150 MORE per phone. NEXT is cheaper than contract over 2 years.
PLUS, it's not clear to me if Nolegirl01 already has the phones or will be buying them, because that definitely affects the "what I have currently" for $160 price. None of these examples seem to be comparing the same thing. The $160 example shows new iPhone 6's, but does not factor in the cost of those phones..
NEXT is the cheapest way, since you get 0% financing on the phones, small monthly payments, the lowest $15/line rate and no contract. $160/mo, two new iPhones, plus the cost each month for the phone installments, no upfront.
They are adding the cost of the phones on next, but not the upfront cost of the phones on the current plan.