I read in bed alot, so I prefer soft, especially mass-market. (I have small hands) If I doze off while reading a hardcover, I invariably poke myself with a nasty corner.
Edit to add; There are also a great many “trade” paperbacks (slightly larger than mass markets) that never started in hardcover editions that are really marvelous.
I love a good hardcover book with good quality paper. It’s an investment, a book I can look forward to having for many years. Softcovers use cheap paper that yellows within a couple years, and the binding is usually just glue, which becomes brittle… and pages start falling out.
I have some hardcover books that are 150 years old and still in great shape, whereas a paperback from as recently as 1990 is falling apart.
Unquestionably softcover. For the reason that @JilltheTooth mentioned. I do a lot of reading in bed, and when I fall asleep under the book, I don’t want to drop a hardcover book on my face.
I stopped buying books as an investment years ago as @marymaryquitecontrary does. I found that I never go back and read them. I buy soft covers at the flea market or at yard sales and resale them when I’m done so I can buy more. Or I will go to the library and check out specific books.
Definitely hardcover. Even though they can be cumbersome, they hold up much better in the long run.
Now that I have an e-reader, I wonder how long before I don’t buy any real books;~)
I prefer hardcover for books I will use as reference. Like textbooks and references that I frequently use. I prefer soft for novels that I will read once and stick on my bookshelf. And I do most of my reading on the bus. So a softcover novel is a bit more friendly in my backpack.
On a purely aesthetic level, I like looking at the hardcover books on my shelves. I’m also afraid of absolutely maiming my paperbacks (my copy of The Catcher in the Rye has seen better days.)
Though I do prefer mass-market soft covers, as @JilltheTooth. I’ve acquired a ton of these for school (I have a leaning tower at the foot of my bed!) These make it much easier to tote my textbooks to and from school.
If I really like a book I’ll buy it in hard cover. Most others are soft cover. The exception to this is when I find a hard cover book that looks interesting in the bargain bin. Then I’ll pick it up.
There are some series that I initially picked up in soft cover and after 4 or 5 readings the binding started to break. Those are the ones I replaced with hard cover the expensive hard covers.
I prefer hardcover. They stand up well on shelves, usually have jackets and are worth more money. I do own softcovers simply because I couldn’t get the book in HC.
For the most part, I go for softcover, if only because they are considerably less expensive. However, there are certain authors I need to have in hardcover. For example, I’m on a mission to get every J.R.R. Tolkien book in hardcover, to replace all my paperbacks. I just got “Mr. Bliss” in from eBay a few weeks ago.