Currently I’m using booky mcbookface but the app is really lacking and the scrolling is not smooth.
Edit: I came across Lithium and Readera which both don’t seem to collect much information compared to other apps. Not sure if they’re open source though.
Readest. But I’m looking for a free app with good TTS and (maybe this breaks the free) which is able to handle DRM content from Adobe digital editions (Or is able to remove the DRM). Unfortunately, my library only provide books through ADE.