I have one good reference book, 'The ultimate Quilters Guide', which is a paperback book that has a wealth of info and techniques. Most of my hoards of books are paperback and I like having them for reference and ideas. Then there are the three magazines I get which also have loads of info but mostly inspiration inside. I use the QB for great tutorials and once again, inspiration. Never used a e-book. I like having a paper pattern in front of me to refer to. I pin it to my design board so it is handy to see.
I choose a book mostly because something in it caught my eye and I want to learn more about the technique.
Every book I own I love, for info, patterns and the shear beauty of them.
peace