#1 You should search the forum first. You'll find a wealth of info on this topic.
#2 If you must repeat a much asked question, you should post in the correct forum:
https://www.mobileread.com/forums/forumdisplay.php?f=184 (maybe a forum moderator will move this one for you).
#3 You should read the Stickies there.
#4 Most importantly, there is absolutely no "best" way to convert PDFs to anything else, period. One, because there is a wide range of possible entities in PDFs and each convert with differing issues so each PDF is its own separate challenge. And two, because there are no "good" methods, much less "excellent" ones, you should search for "the least bad".