Wow I'm surprised no one mentioned moon reader. I have the paid version and love it. It allows you to sync with Dropbox. Which means when I flash a new ROM I don't lose my bookmarks.
I have downloaded Kindle on my gadget because I really love to read and since it is easy for me to use. The books that I wanted are almost here and lucky to have this. I don't know with other Ebook Reader because I am familiarizing myself with all the tools here.
I have downloaded the apps Kindle and Kobo. They are really very nice eReader apps and provide you a whole catalogue of free and paid books, magazines and other materials.