The biggest issue with this topic is finding people who have read the book/seen the movie for the same thing haha
I've found that when I read the book first and then see the movie, I tend to like the book more. When I see the movie and then read the book, I tend to like the movie more.
I usually always prefer the book. That's not to say that I then dislike the movie. Loved both versions of The Martian.
I try to read when I got the time but then there's periods where I'm too busy. But recently one book I happened to read over the summer was Ready Player One and enjoyed it immensely. Now I'm afraid I'm not going to like the upcoming movie. I hope it's great!