Use azw3, it's closer to open and industry standard epub. The reader advantages of KFX are marginal. Main advantages are being able to start reading during slow WiFi/Mobile download and for Amazon, more adaptive encryption. Uploaders to Amazon don't create KFX, that uses docx or epub.
We stopped using Whispernet on bought books years ago (which was KFX) and instead used "Download and Transfer" which gives azw3 (except some old content is mobi/prc). Then later many of us switched from reading on Kindle to reading on Kobo (including ebooks bought on Amazon).
|