Off to the proverbial desert island - which collection do you take with you?
You can take only one (very large) selection of them: Films, Music, Books or Art?
I would probably choose films - sort of the combination of all of the others.
Books.
I can make my own music better than I can make my own books to read.
And I can live happily without films or art for far longer than music or books.
Books.
Books.
I think you’ll likely find this a constant on ‘books’. Possibly with a minority of ‘music’.
Because, let’s face it: books are awesome.
Another vote for books.
I love music, and listen to it all day, but I’ve got decades’ worth in my head, and could face a musicless future with some equanimity.
A movie is over in two hours.
Art is too static.
Books
I can beat on a piece of driftwood and make my own music, but I must have books.
I would choose movies because I would need electricity to watch them. With electricity, there’s a greater chance I could contact someone for a rescue 
must be movies; you have plenty of music in them, if you have some foreign flicks you can get some reading done as well, plus moving images! 
Really? Beating on a piece of driftwood passes for music? No wonder you wouldn’t bring it with you!
Seriously, I can’t understand how anyone could choose anything over music.
The problem with fine art is that, even with a large collection, I can study a piece for perhaps a few minutes, and then I really don’t see much need to look at it again for quite a while. It also has less “after taste”, so to speak, than any of the other options, which makes it ultimately less fulfilling for a desert island. That is important because it needs to be something fulfilling to keep me from going insane even when I can’t engross myself in it, like when I’m gathering food or building a shelter.
Movies are definitely the most involved and “entertaining” of any of the options, but they suffer from shortcomings as well. For instance, compared to a book, there’s still significantly less material to contemplate later. Similarly, movies just generally have less replay value than books or music. For every movie I’ve seen once, I probably have a dozen albums I’ve listened to at least once, and for each one I’ve wanted to see many times, I probably have several albums I’ve listened to at least as many times. It’s not quite the same for a book, but a single well written book will generally provide much deeper characters and plots, along with the very common problem that a book is almost always superior to the film.
Books seem to provide the most bang for the buck of the options thus far, but they still suffer from a problem that they cannot be enjoyed as fully while not actively reading. Similarly, at least for me, while a given book can provide a lot of value, I can’t imagine reading a book more than maybe a couple times.
Music, however, seems to have the best of everything. Not only can it be fully enjoyed while specifically listening to it, but also while doing other things like cooking or working. The “after taste” is virtualy just as good because one can play it over in one’s head or hum or sing it. Moreover, many of my favorite albums are themed albums and tell stories, not to mention the inherent literature in the lyrics as well. Also, similar to fine art, but unlike films and books, there’s a level of expression that music allows. That is, if I’m sad, I can look at sad art or listen to sad music and feel better in a much more profound way that a movie or book can affect that state. I expect that would be especially important on a desert island where finding ways of expression and dealing with loneliness will be important.
So, yeah… music, but a long shot.
The key is to choose books that encourage reflection after you put them down.
Books, of course. Since I can bring a selection, I can include BOOKS of ART.
Movies, because if I’m going to be all alone on a deserted island, I’m going to want animated pictures of people doing all sorts of things, to better retain my own sense of being human and feel less lonely.
Having said that, though, you can bet I’ll choose a lot of films with a heavy musical component, an intellectual aspect, an erotic appeal, and/or foreign languages spoken or as alternate tracks. 
Books.
Books, though music is a very close second.
You’ve never heard me play a piece of driftwood.
It may just be a hunk of wood, but it can function as a proxy for my guitar. I can make a lot of music by any means necessary. There is no proxy for books in this situation. Ergo, books.
Music, movies, books, and then art in that order.
Movies. Of every possible genre, from comedies to horrors to musicals to porn. Especially porn. Lots of porn.
Looking at the OP I assumed my answer was books because I read an awful lot of them. I carry a minimum of 3 books in my car in case I need something to do while delayed somewhere. However on thinking about it I think I would go with music.
A couple of days ago I heard a David Gray song on a TV show, obtained his “Best of” CD and spent hours listening to a few of the tracks over and over. Tonight I heard* DLZ * by TV on the Radio and grabbed Return to Cookie Mountain and Dear Science and I am enjoying getting in to them.
So give me enough stuff I already like and heaps of stuff I may like and music will do me. No light required to listen by, no eyesight even if anything goes tragically wrong.
I’m pretty sure that with enough music to listen to I can put together pretty passable books, movies and art in my head. Well I certainly could in my dope smoking days.