Why not a 30 year loan with extra cash?
I'd stay away from the 15 year loans, only because you're unnecessarily tying up money that has to go towards a mortgage payment - especially when the interest rates are that close. If you get a 30 year loan and make an extra principal payment every month, you basically turn it into a 15 year loan. The difference is that you have the flexibility of not making that extra payment (in case of emergency, life change, etc).
In terms of the chart, "interest saved" is only applicable if the loans are paid on schedule (vs paying ahead). So it's not really accurate to compare. Having a lower payment just means you have more money free to put towards principal in whatever way you choose. The other thing not being taken account is the amount that will be saved just in the refinance! The money saved right there is probably more than the comparison you're trying to do!
I wouldn't evaluate this as "where will I save the most money over the life of the loan" cause there are unknowns. I'd focus on how to best get your rates down without tying up all of your cash in payments that have to be made every month. Personally, I might cover student loan #1 in the refi - there's not many ways to lower rates (unless you think you'll qualify for some sort of loan assistance in the future per law changes).