Simple question really, is の needed when describing genre? For example: ホラー本が好きです or ホラーの本が好きです. SF本が嫌いです or SFの本が嫌いです. The same for music etc. Thank you!
If you drop the の, you are effectively inventing a noun. This is grammatical and natural but will sound a bit colloquial as you are casually creating new nouns. It will also change how 本 is pronounced (
SFの本 -> SFのほん, SF本 -> SFぼん).
You can apply the same logic to music in theory: e.g. 西洋の音楽->洋楽、日本の音楽->邦楽, but you can't quite use it for genres (for example, it's unnatural to say ジャズ楽、フォーク楽、ポップ楽 etc. because the genres are simply called ジャズ、フォーク、ポップ). It also doesn't work with 曲.
Hard to explain why it works for 本 but not with 曲, but in case of 本, there are other "synthesized" nouns that are commonly used (like 漫画本、実用本) so it doesn't sound too strange. In 曲 you don't have such nouns so it sounds very odd.