Hey! Really sorry for taking so long to answer.
I do have some recommendations! Most of them are series of books, because that's the kind of literature I usually like to read, so I hope you don't mind that.
First, is the A Song of Ice and Fire series, otherwise known as the Game of Thrones books. I'm actually currently reading the fifth one from the collection, and I have many things to say about it. There are three things that really make me feel immersed in the narrative. The first one is the characters: I absolutely love the cast from this series. Their different personalities, the constant conflict between them, and the journeys they take really make me feel sympathetic towards pretty much all of them. The second thing is the world: It's a fascinating map, and it really makes the narrative feel alive. And last, but definitely not least, is the really complex and multi-faceted plot. One thing you should keep in mind if you ever want to read this series is there is some amount of violence, sexual content, and language in it.
The Harry Potter books are also among my favorites. The story is so compelling, and the characters make me feel so nostalgic that I constantly find myself revisiting the wizarding world, through Pottermore and whatnot.
And then there's also the Percy Jackson series, which I don't consider as nostalgic as HP or fascinating plot-wise as ASOIAF, but it's still a pretty action packed and fun adventure to read about.
So these are my book series recommendations. If you're looking for individual books, I definitely recommend the Agatha Christie ones. One that I read recently was the Monogram Murders, which isn't actually by Agatha herself but by Sophie Hannah. The initial premise and how detective Poirot manages to put the jigsaw pieces together are really good!
I hope this helped! Have good reads. :)