If you’re for something lyrical/philosophical, I would recommend The Outsider by Albert Camus. If you’re into something more scientific/visionary (and have some brain energy to spare) Godel, Escher Bach (GEB in short) by Douglas Hofstadter. If you’re into sci-fi, anything from Alistar Reynolds. And lastly, you will *never* go wrong with something by Dostoevsky. My favorite by him is Notes from the Underground. Another Russian worth reading is Bulgakov, in particular The Master and Margarit. I hope at least one title would be of your interest. Enjoy!