HTTrack Website Copier is always my favourite. Internet is not always available. Download a website, especially articles, for offline reading is always a good solution. HTTrack is the best. Previously I used GUI, but in Linux, command-line is a better method.

On the other hand, Android e-book reader I used most is FBReader. It supports multiple e-book format, especially EPUB. FBReader is easy to use, and there is night reading mode. Furthermore, it is open source and available in multiple platforms.