
- the PDF is the worst place to start, starting with the DOCX is the best, also much better than RTF and Filtered HTML.
Clarification - the calibre book editor and the Sigil Book editor can co-exist on the same system and you can use both on the same epub - although not at the same time
I do any typographical editing in Sigil mainly because I was already familiar with it when calibre's editor was released, but there are things for which I specifically use the calibre book editor - such as its Links report.
You'll get much better conversion if you use Word's Named Styles feature, rather than inline styling. And avoid using spaces and tabs for horizontal spacing and blank lines vertical spacing. I search the DOCX for things like ^t, ^p^p etc, before I save it - any I find I can normally remove because they're "typo's", occasionally they serve a useful purpose - e..g tabs in a numbered list (after the number).
I find the spell checker in the Sigil editor a useful adjunct to the one in Word, the calibre editor's spellchecker is very similar to Sigil's.
Finally - Toxaris' Word add-on does a lot more besides conversion to ePUB, it's worth having even if you don't use that feature - in particular its Search&Replace and DialogueChecker are invaluable to me.
Added : I forgot, for 'Simple books' I do the conversion from DOCX to ePUB via the calibre Conversion process, for 'Complex books' I use the calibre book editor import DOCX feature. Simple and Complex are subjective assessments - Simple is Novel/Essay-like, Complex is the rest. I use Conversion for Simple because I can do it in bulk either via the calibre library manager or via the command line, whereas the calibre book editor import DOCX feature is a one-at-a-time operation. Most of the 'books' I deal with are Simple.
BR