How are they comparable? Books are a hobby/learning tool, phones are a mode of paying for things/safety measure/communication device/sometimes necessary for your job/calculator/entertainment source/etc. If I had to choose, I can also read ebooks on my phone, so. Books vs TV would make a better comparison I think.
I need phones for so much more than I need a book for. So objectively, phones are more versatile, fun, useful, engaging, and they also last longer than books. You try spending 1000+ hours reading one book, nty. Phones are so much better than books. But I do prefer to read books above reading books on my phone.