omg not to suddenly start parroting the lectures from that one film class i took that specifically focused on adaptations BUT film and book are two different mediums and to compare them too much in terms of adaptations is unfair to both the book and the movie.
a lot of times film adaptations have very different goals to the book (ex. the hunger games books were written as a social critique; the hunger games movies were made to profit off the popularity in dystopian young adult lit; therefore the movies are more focused on the romance than the social commentary). then there are things present in the book that may not translate well, if at all into film, and things present in the film that would have been difficult to incorporate into a book, if at all.
there are movie adaptations that were wildly different to their source material that were still enjoyable and even good movies in their own right, like the lightning thief, bram stroker's dracula, vampire academy, or the nutcracker and the four realms (based on a ballet adaptation of a story). there are movies that are excellent adaptations of books, like the lion the witch and the wardrobe, the outsiders, and the perks of being a wallflower. and there are movie adaptations that are just bad movies (city if bones is what comes to mind).
ALL THIS TO SAY, i like both. i think its fun to see how different people take the source material and expand on it, change it to a different medium, or turn it into something new. generally, i used to like reading books more than watching films, so i used to favor books over their adaptations. nowadays i've started favoring visual mediums a lot more. and since taking that film class i've softened my stance on book vs movies. so i think its good to take a look at both, not necessarily in any order, although i tend to prefer book first (i've been putting off watching the netflix series of unfortunate events and to all the boys i've loved before because i want to read the books first).
[lecture over]