The important thing is to find something that meets YOUR needs. For instance, yesterday I was looking at Spring Design's model. The article went on and on about how great it was. The only thing going through my mind was, "I sure don't like where the page turning buttons are."
Here is a good place to learn everything you want to know about eReaders:
ETA: Overdrive is wonderful! I use it with my nook. I'm going to save a lot of money that way!