I don't generally like to use the word hate for things but I hate harems with a passion, why? because I dislike all indecisive and misleading protagonists, shucks, I hate reverse harems as well. Many of the protagonists in these harems aren't even that amazing in character, even compared with any other guy in that specific anime, they just happen to be the protagonist is all.
I also hate when they make many seasons of generic, no substance anime (I won't name any so as to not rattle the hornet's nest) and they leave really good anime floating in the water after one season.
There are some no substance anime that's out there just for laughs and makes you feel good. I don't really hate them but it could have been better if they have some good plots.