cnepub the best at least ont my smasung 10.1 tablet - and I read lots
there is an app that works for phones Nexus4 ok android 5"phones. quite intuitive as most documentation is chinese ! moonreader pro on the rare times (1 out of 500, there is a problem and it core dumps. Usually on some epubs that are are very big (like 6 books in 1) but then not always. then I use something else until 1 will do it.
I convert anything to epub via ebook converter (from /to any format) took me some tme to find it(icecoldapps.com)
I dislike being tied to one environment like kindle. Books and docs (I work on systems, are with me at all times. I read in the train , metro , bed, week end - so the app has to really be good.
Try CNepub it is free
epubReader - Android Apps on Google Play
https://play.google.com/store/apps/details?id=com.cnepub.epubreadera