Star Wars is now a collective work and GoT is the work of one man, I'd say GRRM has done more worldbuilding than any individual Star Wars director/author/comic writer etc. and arguably he has done it better than all of them... but due to the collective nature of the Star Wars worldbuilding, obviously Star Wars has had better worldbuilding despite the inconsistencies.
Star Wars. GoT has very good and very tight worldbuilding, considering only one guy has really been working it, but it lacks the sheer quantity that Star Wars has, due to its age, the number of fingers in the pot and the way it develops its history; ie, fleshing the hell out of multiple eras. That being said, GoT even falls behind some other works done by single individuals (ie, Tolkien's legendarium).