I still think the return-on-time from a good book is greater than a lecture or video or discussion. There is just so much refinement and information density, plus the ability to skip around to find interesting content is hard to match. (there is also something to be said for reinforcement of memory via spatial awareness while reading a physical book that is lost on a screen).

An interactive portal to a digital book could rival or surpass the experience, but I haven't encountered that yet.