Personally, I think that reading books is better.
First of all, films are usually based on books. I believe that it is better to read a book, if you want to understand the author better. I watched a film called "12 Chairs" and then read its book. Well, the film is not bad but the book is much better.
Second, reading develops imagination. It is as though you create your own film and not passively accept someone else’s vision. "Tree Musketeers" by Alexander Dumas, created in my brother's imagination was so good that he could not even finish watching the film version.
So, that’s why I think that reading books is better.