We settled on KOReader - I announced it here: https://www.mobileread.com/forums/sho...d.php?t=209276
Please continue to discuss the stable legacy code base in this thread - and head over to the new thread for discussing the new code base.
A note on the old code base: We have restructured the repositories. The new location is https://github.com/koreader/kindlepdfviewer
(we switched to an organization account for the development of the projects).