There is no single answer to this question. Actually the question is wrong, but I’ll go ahead and write an answer anyway. In fact, I want to write a couple of things as I think about the books I’ve read so far. These may help me pick my future books better, or who knows, you may want to send me suggestions?
Ok, rule number 1: dear writers, please, please, do not go into pages and pages of descriptions to make the setting more plausible, or believable, or whatever you call it. Don’t! Good books give that feeling without describing every little detail in the surroundings. When the main character is walking towards a key meeting, or a very dangerous encounter, the last thing I am interested in, is the history of the city/planet/road/town/whatever the character is in.
What was absolutely brilliant in William Gibson’s Neuromancer and the following two books of the trilogy was that, they made you imagine the surroundings without boring you to death at the wrong time in the story. I am seeing way too many sci fi books these days which take four times the amount of necessary pages than it is necessary to tell the main story.
I’m sorry, but if your creativity is not good enough to make “what is happening” interesting for the reader, “where it is happening” is not much of an interest to us, at least not to me. Inner struggles, thoughts, memories, all fine, just don’t fill pages with descriptions of the city please…