Well, from the choices of animé I've seen... Diabolik Lovers. The protagonist is annoying and bland, the very little storyline it has is extremely chunky, and the exact same thing happens every single damn episode. Just annoying little Yui getting her blood sucked par one of the hot vampires. (The vampires had decent personalities, though. Ayato was hot.) It just bored me so much and I couldn't really get into it.
I frikkin' hate School Days, it was just incredibly irritating and boring to watch and it had the worst MC in the history of MCs. At least it had a reallly satisfying ending MDR X) I also hate animé which it's only selling point is fanservice such as Highschool of the Dead, Highschool DxD, etc. Screw those series.
I hate every animé in existence. The artwork is bland and the stories are to one dimensional. Like I have no idea why anyone would watch that form of entertainment.
Ahem..honestly I don't have an animé I hate anymore. My hatred is plus centralized on individual characters. If that was the question. I am certain I would be able to supply numerous examples of characters I abhor.