L C Knights was an English literary critic, an authority on Shakespeare. He said a good novel, 'Makes me walk more in the world.'
J F Kermode, another Cambridge man, was a British literary critic best known for his work The Sense of an Ending: Studies in the Theory of Fiction. He judged a novel to be good if it was re-readable.
I am in the world of a good novel days after I have finished reading it.
Also one that makes me smile fondly as I recall it. Death going out for a curry in the Discworld novels, for example, just flitted into my mind.
The ones that give me a full-body reaction to what has been written. For example, I still get the urge to argue wildly with Professor Umbridge in the Harry Potter novels and would dearly love to wipe the smugness off her face. I also feel very sad when I read about Mrs Dubose in To Kill A Mockingbird, feel a certain respect for Granny Weatherwax in the various Pratchett novels and would love to go out on a hen night with Nanny Ogg just for the fun of it.
One where you just get lost within the author's world, are sad when it finishes and can't wait for the next in the series or from the same author.