I have the eBookwise reader, a primitive reader that still has some zip; I've got the Kindle... and I have a tablet netbook. Of the three, I prefer the Kindle for it's long battery life and clean screen. It's currently got over a thousand books in it. (Many free older books are available, some directly from Amazon!) I like the Kindle better than the nook, mainly due to it's faster page turns. Nothing kills the moment like having to wait for the screen to refresh.
All that said, I like my netbook for it's versatility. With it, I can read using Kindle for PC... or watch movies, play music, cruise the internet, play Runescape, or... write a hub :^)
... Oh, and the eBookwise reader? I like its touchscreen, and backlight for reading in bed. And the pages turn like lightning. All excellent features.
It's all about what your needs are. But for pure ebook enjoyability, I choose Kindle.