Even if handled poorly, I'm fairly certain this will put a hurt on the Narnia franchise - the story and characters are far, far more compelling.
As for which is more compelling; I haven't read The Golden Compass (though I plan to soon), but I would imagine it would depend on what you find compelling in general. The Chronicles of Narnia do not have an overabundance of character development, nor should they. They are philosophical and very abstract in nature, and make some very broad, very meaningful points about God and mankind. They are stories in every sense of the word, whereas I would classify many modern tales as mere plots, if you follow.
Nevertheless, I hope to read the book soon and see for myself.