Moash and Sadeas were clearly made to be hated, and they are extremely effective in their role. And I think one of the reasons why is because how convinced yet wrong they are.
Although, the character I truly dislike (alongside Moash) is Shallan, mostly in OB, because how much screen time she has, and how boring her chapters were.
In the other books there's no character I dislike actually. Well, maybe Elhokar in most of WR, because he is an idiot.