To read mobi on Windows:
Code:
FBReader - https://fbreader.org/
Simple, faster
STDU Viewer http://www.stdutility.com/stduviewer.html
Kindle for PC https://www.amazon.com/kindle-dbs/fd/kcp
Sumatra PDF https://www.sumatrapdfreader.org/free-pdf-reader.html
(issues opening some MOBI files I have, not all)
Freda http://www.turnipsoft.co.uk/freda/
(Note: its an Windows store app... with ugly interface but configurable!)
On books: I do prefer ePub over Mobi.
On Calibre: I don't read that much on Desktop PC but when using PC I consider Calibre mainly a book organizer not my main reader app