It's genuinely magic to read. And I really don't feel like anyone has matched his authenticity in the fantasy genre.
I love C.S. Lewis, but the Chronicles feels very artificial. A new venue to preach his religious motives. Fun, and well done for sure. But not the same.
I also love the Steven R. Donaldson series The Chronicles of Thomas Covenant. It's a moral journey just as LoTR and Narnia are, but it's a deeply personal struggle for a guy trying to manage his own mix of character successes and failures, rather than epic characters who each represent one idealized version of a human trait.
But as much as I love that series as well, I feel very much like the world was created for the story, and not at all that the world was created simply to create a world, and the story was created for it.
Tolkien really did it perfectly. I don't know that he ever intended to do what he did. It could be argued that it's not really correct to call him a master at his (or any) craft because he wasn't trying to do anything like what he did. There's a certain accidental quality to it. Which is perhaps what makes it so compelling.
It drove home the scope of the fictional world that Tolkien created.