The is no such thing as a "good" way to convert PDF to any editable format, document or true ebook.
I recommend that you give calibre (
https://calibre-ebook.com/)a look and check out the forums at MobileRead (
https://www.mobileread.com/). calibre is an excellent ebook format converter, editor, and library manager.
The problem converting PDFs is that they rarely have text in any logical arrangement of sentences and/or paragraphs. Many PDFs don't actually have any text, having vector are that looks like characters or even just bitmap "pictures" of characters or whole pages. There are so many possibilities in how a PDF is constructed that there is no way that any app can reliably read the mix of text, vector graphics, and images and create a flowing text without significant errors.
The most common "decent and best available" methods involve experimenting with importing the PDF into a good text editor (e.g. MS Word, ...) and exporting either HTML or DOCX from there and using calibre to convert that to epub before editing the epub in calibre's editor or Sigil to clean up the errors. Other "decent" methods for dealing with a pure image based PDF (scanned books, ...) is to use an OCR (optical character reader) app, like on of the ABBY... apps, to "read" the scanned pages and output text. The results will always contain a sizable number of errors that you'll have to manually fix.