Mine is the wings of fire series, it is a “kids” novel (think like warrior cats age range)
But Tui T sutherland is so good at writing characters and introducing and describing worlds and characters that i reread it every so often. Like, she managed to write a book from the pov of a mind reader and it works.
Every book is from a different character’s pov and each character feels wholly unique.
The main issue with the series is that the plot is kinda average at best, the characters really carry the story.
Sabriel by Garth Nix. I like YA novels in general; this one and its sequels are amazing. The world building is so good that it feels more like reading a folk tale than a fantasy novel. Also, I like that the main character stays in the picture as an adult and is shown dealing with regular adulthood problems.