Project Gutenberg is quite a popular name in the e-book club. It's a charity endeavour run by volunteers and fundraisers, and most of its library contain public domain titles. The ebook site has over 60,000 free ebooks that you can download. It supports EPUB, MOBI formats, and HTML as well. It has a range of audiobooks too, and the library is segregated into categories, although navigating through them can take up some time.
Media365 Book Reader
Media365 Book Reader is one of the popular ebook apps on Android. The interface is simple and vibrant. The app supports a number of formats including comic book, and you can customise the font as per your preference. The app offers an array of genres to select from- non-fiction, biography, comic, among others. Although to get access to the popular content you will have to make in-app purchases, most of the books are free.