I own 2 e-readers, 1. kindle 3 wifi only, broke and replace display (1 time) and then bought 2. e-reader device - wexler flex one.
First is good because of audio, battery life and dictionary, second because of 8gb -> huge space for eBooks, and multitude of different formats (pdf, mobi, epub,...) and flexibility ( durability ) of display. And don't forget its weight
Flex one has higher resolution, but there are more leftovers from last viewed page. Battery life is a lot worse then kindles(only 5-10 days)! But none e-reader can compete with flex one because of non-breakable screen, I sat on it and even sleep on it one time and still works
Price is more or less same after tax.