Hi Linsey and welcome! The best e-reader is the one that meets YOUR needs and wants the best. Take a look at
the matrix first to see what's available.
Then sit down and write out a list of what features are important to you for what you want an e-reader for. Everybody's list is a little different - you may or may not want 3G or wifi, and you might decide certain other features are do or die.
You may also want to take a look at Calibre before you make your decision. There's a whole section here on Mobile Read devoted to Calibre, and playing around with the software (it's free) can give you some ideas what you might want to use an e-reader for. (I know it helped me make my decision.)