Librera is the one I’d recommend if you care about customisation, and it also has TTS (Text To Speech), which is why I use it almost exclusively.
Myne is a beautiful and minimalistic app that lets you read books from the Gutenberg project. I have asked the developer, and they have no intention to add TTS functionality to the app.
Shosetsu is the best app for fanfiction (AO3 extension) and lightnovels. It recently got a TTS feature as well, but that feature is not very usable in its current implementation.