For me the most important feature is the pdf support and on that account, Nook wins. Its pdf support is much better than Kindle, supporting reflow. that way, you see the page as the native format with real page numbers. it is quite readable if your file is basically text. I don't know if Kindle has improved in this regard but when I bought and returned Kindle DX six months ago, this feature wasn't there and pdf looked more like an image than text. Even DX's large size did not help me read pdf books because it was small and dimmer than regular text. Now on Nook I can read them as though they are in native format. no conversion is needed. but again these are mainly text-heavy pdf files, not complex, graphic-heavy ones.