I want to say the worst comment is silence. It is like saying your series is not even worth being disliked, it deserves to be buried down deep for nobody to ever know it exists. At least with hate or unpleasant comments, the other side thinks it worth to spend time and effort on shitting on.
Also some comments I have gotten from different discontinued series:
"Which is better? This series or another series?"
(I usually ignore these kind of comments, I don't even know what does it mean.)
"I don't understand this shit."
( While their presentation can be shitty, this comment do not piss me off at the slightest.bI will try to explain and ask on what makes it unclear. Then I will ask other readers privately about the commenter's point for second opinions and edit my series accordingly. If readers do not understand shit you write, can you even call yourself a writer?)
Please write more bad comments to my current series, I want to feel alive