Me personally, Angel Beats. If only it has more episodes, it would have a strong impact on me. Please comment the reason too instead of just the name :)
What anime that people rates highly but you don't?
There is quite few anime series what I don’t rate high.
Naruto (Shitpoopen also): Too slow based, flashbacks after flashbacks. Even after Manga ended anime delayed finishing for two years. Never actually finished anime. Read manga and it was ok.
One Piece: Too many unnecessary characters. And who the hell uses over 100 episodes on one arc? What all happens in one day? So slow pace in anime that it’s pretty boring to watch. But don’t know why I’m still watching it?
Attack on Titan: Art style is good, and have to praise it. But characters are sadly pretty boring, and story. At first it was really good but after 5-7 episodes it got boring.
There is even more what I don’t like but I leave these for now.