All other things being equal–do you prefer used books? Or new books? (The physical specimen, that is, not the title.) Does your preference differentiate between a standard kind of used book, and a pristine, leather-bound copy?
While I do love the smell of new books and the feel of a new dust jacket under my fingers (I don’t care for leather-bound copies; it makes me think of antiques and get nervous about reading them), I prefer used books. As an enormous speculative fiction fan, I’m used to mass market paperbacks from the seventies and eighties, its pages yellowed and mildly crumbling, its cover sweet ridiculous, and sun damage on the page. While I didn’t enjoy The Once and Future King, I got a huge kick out of imagining the first owner—she clearly read the book while in a park, given the sun damage. I love that sense of history and community with other readers. Reading can be a solitary pursuit; why isolate yourself?