The link below is to an article that lists 15 ebook reader apps that the writer considers the best. As always, check out the comments section below the article for ‘alternative’ views as to what is the best ebook reader (oftentimes not listed in the article), especially if what you are after is not in the provided list. However, you should be able to find what you need in the list provided.
I, of course, use the Kindle ebook app whenever I need to use an app, though generally I use my Paperwhite. I do find the Moon Reader + app to be a very good ebook reader app also.
The link below is to an article that looks at reasons to upgrade from a Kindle App to a Kindle Ebook Reader. This is something that I did a short while ago (I did have a Kindle Ebook Reader from the start – which was no longer any good I should add), simply because I wanted something with a longer battery life. I would probably have been quite content with the app on my tablet otherwise.