I am in quite a few fandoms and it seems almost any anime manga or tv show has way more slash than het. ATLA is something i never got into ship wise because it squicks me, and because i had friends start fights over kataang or zutara. But just to name a few slash majority fandoms: SPN, One Piece, Bleach, Harry Potter, DMC Etc. Some slash fangirls try to act like they are being oppressed in the fandom world when it is clearly not true.