I see Steinbeck's East of Eden on your top shelf. One of my favorites -- I have the same volume. (I love book shelf photos. You can learn so much about a person.)

Just Kids by Patti Smith, a beautiful memoir!

I don't have any one book I would recommend as a permanent addition, but I think it would be a good thing to have a section where books regularly circulate through your collection. Don't let any one genre, medium, or author dominate your collection. Don't get stuck in a rut. Times I have stopped reading occurred when I had binged one author too much and got fatigued with their style. It is bad when you can predict where the author is going. Mix it up. Here is some fiction, sci fi, magical realism, non-fiction, comic memoir, titles that have moved me. I did struggle sometimes with these books, but I always thought it was worth it at the end. The Left Hand of Darkness by Ursula K. Le Guin Salvage the Bones by Jesmyn Ward The Brief Wondrous Life of Oscar Wao by Junot Diaz Fun Home a Family Tragicomic by Alison Bechdel Just Mercy by Bryan Stevenson Freshwater by Akwaeke Emezi The Blue Sword by Robin McKinley