Recently I discarded all of the Harry Potter movies that I've had in my collection. I had the mainline ones and two of the three Fantastic Beasts films. But, as much as I have liked the visual representation of what the films projected, I didn't feel that they were faithful adaptations. Because they changed too much for my liking.
Instead, I prefer the books because they do have better character representation than the uneven scaling of how the characters are in the movies. That's what I found important than anything else between book and film. If anyone were to ask me as to what exactly is the best way to get into Harry Potter, I would say the books, because they're going to get mislead by what the movies project. Is it the best optimal experience of the universe established.