Both the alternative reading programs are using Coolreader 3 to render .epub files. Koreader also has improved .pdf, .djvu, .cbz rendering. I keep 7 to 8 thousand ebooks on my AuraHD in a file folder structure that lets me drill down from type (Action, Fantasy, Mystery, Politics, SciFi, ect...) to subtype to Author, series, book. But I don't have any reading statistics, awards, or social media connections. Not things I want included in My ereader. Both are fully functional (For Mark4 devices, like the AuraHD, but not yet for the new Mark 5 Aura) but being improved all the time.
Luck;
Ken
https://www.mobileread.com/forums/sho...d.php?t=226456