If at all possible, use the DreamSpark Premium. Microsoft won't take it away when you get out of college, I can still use all my software from DreamSpark.
This also means that you get to keep your windows 7 license. If you were to upgrade using the windows 7 license, you would loose that windows 7 license in exchange for a windows 10 entitlement. This way you can go back to windows 7 if you find you don't like 10.
Also remember that windows 10 uses entitlements. This means that once you install the OS, it's tied to that hardware. Upgrade the motherboard and you will have to buy the operating system again.