I prefer paper books for the same reason as you do, too. Being able to flip through to check back on things easily helps me digest the information better. Furthermore, non-fiction page number may be misleading on ereaders. For example, it may show as 500 pages, but the actual book material is 300 pages, with the rest being diagrams and the annex, etc. This is quite frustrating because I like to estimate reading length and having control.

On the other hand, ereaders are great for reading fics, borrowing ebooks from the library (it saved me many physical trips), and being able to carry a lot of books around. I love my kobo and wouldn't leave home without it.

Audiobooks are an absolute no go. It's quite inefficient, and I just can't process information via audio very well.