World Exploration has been pretty good to me. I've gotten 3 new gold knights already and today I got a rainbow Longstalk Holly: https://flowerknight.fandom.com/wiki/Longstalk_Holly
Edit: just after I wrote this, I drew 2 more new gold knights (about 50 or so remaining). Are new knights prioritised or something?
As for the event missions, I found that a significant part of the overfarming comes from the bonus stages, actually. But then again they give manyus and life crystals, so I tend to do them regardless.