All other things (like price and storage space) being equal, given a choice in a perfect world, would you rather have paperbacks in your library? Or hardcovers? And why?
Whether I buy hardcover or paperback depends on many factors - and it is truly impossible to answer the question without taking price and space into account as those are two of the biggest. There are certain writers whose books I want to get soon after they come out - if Ethan Canin has a new novel or Pat Barker (just bought her new one - can't wait) I want to read them right away, I want my purchase to impact the book's sales, and I want them to be paid for their writing. They're both probably deeply and personally grateful to me for the 11 cents they receive from the sale of a hardcover edition to moi. When each new Harry Potter book came out, I didn't want to wait until everyone else had read it and ruined the ending for me, so I bought it. There are other books where the hardcover edition is beautiful enough that I want it as an object - The Invention of Hugo Cabret was such a book. It had beautiful paper, lovely illustrations - it was a satisfying object to hold. If I get a book from the library I tend to want it to be hardcover. Library paperbacks generally show their age more. The covers are all wrinkly and the pages coarse and yellowed. They often look to me as though they been used as a teething ring or a hanky. Yuck.
However, there are some books I prefer in paperback. I usually buy my Iris Murdoch books in one place - the antiquariaat boekmarkt on the Spui in Amsterdam on Friday mornings. On my way to work, I stop off and browse the stalls. Usually there are at least one or two that have a good selection of old English paperbacks - usually the old Penguin editions. Those are my favorite Murdoch editions to have. It's fun to read the blurbs from the British literary critics and to read how the book was sold when it came out in 1967. Often the books were sold on her writing prowess, her last success rather than now when they can be sold upon her iconic status as a famous dead victim of alzheimers who was played by Judy Dench. Yawn. The old Penguins have held up pretty well, they look nice on the shelf and their easily portable. I also enjoy the New York Review of Books paperback editions - they're printed on beautiful paper and have lovely covers. They are simply nice objects. I have never seen a new Tolstoi or Dostoyevski translation by Richard Pavear and Larissa Volokhonsky in hardcover - do they exist? All of mine are attractive, large format paperback - and it's probably just as well given their length. I've had my edition of Anna Karenina for at least 15 years and its still in great shape - not yellowed or creased.
I own a lot of Dickens in paperback because I have picked them up in used bookshops but I'm not happy with any of the editions I own. The bindings are in bad shape because they've crammed so many pages into them. The text is squeezed onto the page with the tiniest margins as if the publisher thought if there were ten more pages no one would ever buy it. I want to start getting my Dickens in hardcover - despite the price - because I want to keep those books and I want to re-read them - and with some of the editions one more reading was all they could take. If I read my edition of Dombey and Sons again I would just have to discard each page after I read it because they detach from the binding as I turn them. So I want my Dickens in hardcover now. Preferably in nice editions, if you're considering getting me one for my next birthday.
But price and space are a big issue. If I'm traveling I always read a lot, but I prefer to bring paperbacks. They're lighter in weight. If I buy books while traveling, I'm more likely to buy paperback for the same reason. I live in an apartment, so space is an issue - all things are NOT equal regarding hardcover and paperback. Price can be an issue, but with plenty of opportunity to buy books at a discount or to borrow them from the library, it's usually more an issue with textbooks than any of the other stuff I read. I can save $40 or $50 with a paperback edition. And some of them are badly enough written that I will probably never consult them again after the final exam. And the prices for textbooks are nuts! Instructors get free copies and students pay over $100 - who made up that system? Thank god for India which is now producing cheap paperback copies on newsprint of many textbooks which, although they are illegal to sell, are readily available and have saved me tons of money. Another issue is not space on my shelves but space in my bag. I want to have a book with me at all times, but having suffered one incredibly bad case of sciatica, I have to limit what I carry with me. Most people still think my briefcase weighs a ton, but I refuse to be caught somewhere without something to read, so long live the paperback edition. But ultimately a book is a book, and provided it doesn't fall apart and isn't too greasy with something that sets my imagination running, if it's good to read I'll like it whatever the binding.