I wat a lot of films but my favorite anime is "Attack on Titan" (Đại chiến Titan) by Hajime Isayama. It's a fantasy story set in an imaginary world.
It's the story of a world where humanity lives inside cities surrounded by enormous walls that protect them from gigantic man-eating humanoids referred to as Titans. The main character is Eren Yeager, whose mother was killed and their hometown was destroyed by a Titan. On the way to find out the Titans, they know an unbelievable truth but I won't give it away.
I liked the book for a number of reasons. The author has created an amazing fantasy world. The story is very gripping and I found it difficult to put down. The characters are convincing, I identified strongly with eren. I highly recommend it.