Do yourself and favor and forget about taking another loan to pay off your student loans. Your job should be to get rid of your loans ASAP, and only then start thinking about buying a house, etc. This may not be what you want to hear, but getting out of debt should be your #1 priority.
As far as which loan to tackle first, I would probably go after the $7k one because of the high interest rate. I wrote an excellent guide
on getting out of debt fast. You don't owe that much and with consistency and discipline you will be debt free in no time.