I used to always prefer physical copies, but I have started using an e-reader over the past couple of years and have found it to be super convent. I borrow ebooks from the library, which saves me time and money, and I don't have to find space to store all of the books.
I don't read books, but I read a lot of reports about things (various railway things, etc). I always prefer them in PDF format, as they can be quite lengthy (>500 pages)
I like physical copy of a book. I like to maintain a library. I once had a library of 5000 books but sadly I lost books as I moved places. These days I mostly read ebooks. It is easier to store.