Updated: Mar 10
Comparing book formats superficially involves four factors.  Transportability  Affordability  Readability  Longevity. Ultimately all these ‘itys’ crunch down to two - SPACE and TIME and as Kipling would have said, referencing Einstein, 'we must treat these two impostors just the same,' books are about SPACE/TIME.
Hardbacks are heavy, cumbersome, expensive, tend to have larger text, better paper, a robust sewn binding and therefore last for ages, literally in some cases. I once owned a Book of Common Prayer, at 450 years old, still perfectly readable. And you can repair/rebind a hardback to extend its life even further.
Paperbacks tuck in a pocket or handbag, they are cheap to produce and buy, they are printed on cheap pulp paper which suffers from UV degradation, going rapidly brown with age, and the glued binding rapidly disintegrates especially if you read them in the bath, I have dozens of paperbacks thirty years and older which I hang onto for sentimental reasons, read them and they’d crumble to dust.
The jury is still out on better end print-to-order digital paperbacks. They are generally printed on 120gsm paper, traditional paperbacks on 80gsm if you’re lucky. Factor in the dry digital printing process, and they may well enjoy a greatly extend life. Only time will tell.
Conversely, digital hardbacks use fake stitching, in reality their binding is glued, and this will limit their lifespan, especially when read in the bath. Again, only time will tell.
eBooks, are weightless, cheap, readable, indestructible, and come with the added benefit of being unlosable.
Audiobooks are not books.
Call me crazy, but if I come across a book I really like I’ll buy paperback, hardback and eBook. On ABE Books and Book Depository a second hand hardback can be considerably cheaper than a new paperback. Inseparable from SPACE/TIME is MASS. I may soon need to get my floors reinforced.