Characters that you want to read more about as it means the writer’s carried out their work properly.
Characters you can easily recall and perhaps secretly wish you yourself had invented.
A good sense of the world the author's created for me to see. I want a damned good look at it! I want to be able to see in my mind's eye the system of government, how the society is organized, some sense of the realm's history especially if it has a knock-on effect on the time period in which the story is written.