For non-fiction, I still passionately believe physical books to be a superior UI. It is simply faster to flip between half a dozen open books on my desk for research than it is handle pdfs, e-readers, browser tabs, etc. For reference material it also secures your supply chain from the whims of publishers or distributors - you self-custody the knowledge in your home or at worst a university library. I will admit that lack of CTRL-F hurts, though.