Best Tablet/e-reader for University

So I'm thinking about buying a tablet probably sub $300 mark to use as a replacement for textbooks.

Since digital text books are cheaper and textbooks can be annoying to haul around I was thinking it's time to make a switch.

I don't really care about screen size (whatever is best for reading) and I guess the main one is battery life and functionality. I would definitely want it to be an android one and have the play store.

I appreciate any suggestions some I was thinking about possibly the Google Nexus 7 and I would think about the Kindle Fire HD if someone convinced me.