The Stormlight Archive is a series of books about a group of people, the Radiants, who begin to discover they have super powers. They learn that their powers are the same as those of the ancient Radiants, who were trying to protect humanity, but eventually gave up. The characters realize that they must now protect humanity from the disaster the ancient Radiants were trying to prevent, while trying to change public opinion about the mistakes the ancient Radiants made.
The character development is what makes the series great. Each character has two sides to their personality: their current better self and a bad past they are trying to overcome. The constant struggle between the two sides of their personalities is incredibly interesting. Their struggle feels realistic, because although their personal issues improve, they never really go away, much like in real life.
Another reason I like the series is that it is part of a larger universe. The author, Brandon Sanderson, has written several standalone series of books, however, they are all connected as part of the same universe. The universe has some general rules, but each world has different manifestations of these rules. You can read each series individually, and even if you read several of the series you might not realize they are connected. Once you start looking for connections though, the reading becomes a lot more interesting. You begin seeing the general rules of the universe taking effect, and some characters popping up in multiple series. This is intriguing and I am constantly looking for new connections, or learning new things about this universe on the universe's wiki.