MagiStream

Of course the question is impossible to answer the way it's worded because this is a very subjective topic. A discussion about what book genre IS the most interesting could take many hours and lead nowhere, so of course I can only answer what book genre I personally find the most interesting.
Generally fantasy has the potential to be the most interesting. The problem is that much of modern fantasy is rather shallow and all the same. There are of course still many exceptions from that, but you have to search for them.
Also: possibly an uncommon opinion, but semi-humoristic children's novels. These are the most entertaining to read, to be honest. With that I mean actual children's novels, not young adult novels. (Actually, young adult novels are usually some of the worst books for me.)

Uh.... that is a bit hard for me to decide as I really love a lot of genree types and thend to write also in many of them... though to be honest I never could get into those adventure type stories which involve the wild west which my father likes.

Fantasy is able to bring you into different worlds togehter with sci-fi, but with different, rarely intercrossing perspectives. If the auther is good like Tolkien the world they build becomes just as much of a reality as is the one we live in.

Mistery/Detective, it is one of the earliest genrees I have read so it it pretty close to me. I was actually happy when during an Antiquarium shopping trip I fond "A century of detective stories", it is pretty old and a bit damaged so I treat it carefully, but still a great book. I love the classics from Sir Arthur Conan Doyle, Poe's mysteries and even a bit more modern ones writen by Umberto Echo. Got his "The Name of the Rose" also from the same place as the above mentioned book incredibly cheat due to the cover being a bit damaged.

I also got a bit back into my Lovecraft and his cosmic horrors and will probably also read some stories from his fellow authors with whom he was close with, I especially like "The Hounds of Thindalos" and "The Bells of Horror" from which the later would make one great film.

I like the fantasy/manga genre if that is a thing

Speculative fiction for me. Sci-fi, fantasy, alternate history, all that stuff. Not horror though. I don't want my entertainment to give me a panic attack.