As a writer, I often ponder the books I've kept over the years. Of course, now that I have a Kindle, I can keep a ton of e-books, but these are paperbacks and hard covers, taking up space on my bookshelves.
I keep them organized by author. Just glancing at them as I write this, I know what makes a story something I want to read over and over again. It's not just an author's ability to spin a good tale; it's not just awesome description, or world building. Yes, all of those things factor in, but for me it's all about emotion.
I read and re-read books where I care about the characters. Bottom line. For beginning writers, sometimes I think that's the hardest thing for them to learn. No matter the genre - historical or suspense, paranormal or western - it's the people who matter.
I love reading a book where I'm cheering for the character. I adore an author who can make my heart ache as I read about the hero and heroine's love story, or problems. This, more than anything else, makes me keep a book rather than giving it away or trading it in at the used book store. And I know there are certain authors who will deliver this consistently with every story.
Some examples of my auto-buy authors: Kristin Hannah, Kristin Higgins, Barbara Samuel, and Lisa Kleypas.
What about you? What element of a story makes you want to keep the book and re-read it? Who are your auto-buy authors? Don't be shy. I might find a new author this way!