I think that it's quite reasonable to consider Tolkien as one of the best world-builders in the Western canon. But that is unsurprising, given that the man basically devoted his entire life to constructing a single imaginary world - he was a world-builder first, and writer second (and far better at the first than he was at the second, IMO). Most authors create a world to tell their stories in, and it's only as detailed as the story needs it to be. Tolkien wrote stories as, basically, illustrations to his world-building. Most of them didn't even get cleaned up to be publishable until long after his death.