Oh, how I loved adventures! Now I'm more into mythology... My favorite writers in this genre are J. London, especially "Heart of Three," Haggard's "King Solomon's Mines," and Defoe's "Robinson Crusoe." I also really love Sabatini.
From mythology, I like the Germanic epic. "The Song of the Nibelungs" is amazing, both as an opera and as a film based on it.
In science fiction, of course, Herbert. Also, the Strugatsky brothers and Bradbury.
In fantasy, Tolkien ("The Silmarillion" is great) and Le Guin.
"Harry Potter" is a Greek tragedy in a magical setting. And the English in the 6th part is something else. Soon it will be a classic of the language, just like Lheroux or Salinger is now.
Classics: "A Hero of Our Time," "The Hunchback of Notre Dame," "Les Misérables," "Faust," "The Divine Comedy," "The Phantom of the Opera," "Dracula."
Once upon a time, "The Lives of the Twelve Caesars" was my go-to book, but not many people read it.