Well here is a list of people who have gotten flack for things they have done / ways they have acted in the past (they may not be the most hated now. But they used to be anyway)
Akay - leaked content and is a complete Aoki wannabee
R00t - Was a complete skid
Maiki / meh - Acted like a dick to many users. He was my friend, but a lot of people hated him
Rikka Chan (idk his name now). Got perma banned for leaking content to his site. Then tried coming back with ban evade accounts.
I guess if we are talking about the most hated NOW? That would have to be Tragic. Because his recent thread has repfucked him