But I tend to dislike the overarching glorification of Tolkien. Surely an impressive writer and world-builder but surely not the only one and not necessarily the best.
Instead -- I suggest you watch some of his live action adaptions! The Smiling, Proud Wanderer is my personal favorite JY story, and my favorite drama rendition is the 2001 one starring Li Yapeng. He is probably best known for the Condor Trilogy (The Legend of the Condor Heroes, The Return of the Condor Heroes, and The Heavenly Sword and Dragon Saber) and although I loved the first I was never personally that into the latter two of the series. Probably his greatest work is in my opinion Demi-gods and Semi-Devils, although that might not be a good entry point into the series. I would look at TSPW or TLCH first :)
And well, Tolkein will always hold a special place in my heart. But I do agree that he is slightly over romanticized as an author.
So as always, if you want to have a taste of his work, movies are your best friends. Below is a good one:
Ironically, Orwell wrote before WWII that Aldous Huxley's Brave New World (1932) was heavily inspired by We (1921). Then he wrote 1984 (1949) which borrows even more: it's the same story, with more romance and a more mainstream narrating style.
Tolkein presents an extremely fantastical view of the world and ascribes to what I call "cosmic morality." There is obvious, pure good and pure evil, and in a way the Universe intervenes to make sure that pure good will win out in the end. I don't mean this in a Deus Ex Machina way, by the way, as cosmic morality is justified within Tolkein's universe. I think Breaking Bad is a good example of this as well -- the Universe has passed its judgment on the characters it deems necessary to pass judgment on, and it works within its story without detracting from it or seeming like a Deus Ex Machina. So much of the criticism of Tolkein in the modern day, to me, surrounds this concept where he ascribes to the idea that the Universe will eventually judge sinners and saints. That being said, it does not and should not detract from the sheer magnitude of his creative work, as well as his linguistic ability.
George RR Martin, is, I think, an obvious counterpoint and much of his writing is driven by a distaste for this amount of cosmic morality. If we were to harken back to amazing TV, GRRM is more like The Wire -- they choose to present the world in a way they deem "factual". But in doing so they lose some of the higher fantasy elements that Tolkein's world building is known for.
So I think when you ask the question of who is a better world-builder I think you need to start with asking whether or not you want a cynically real depiction (ala GRRM) or you want a story that justifies it's heroic deeds (ala Tolkein) first. Because, in my opinion, they are hard to compare.
There is no such thing in either the Silmarillion or the Lord of the Rings: in the Silmarillion, Melkor is taken beyond into a different dimension, yet there is so much damage that this is hardly more than partial damage control; and stopping The Enemy causes an even greater tragedy, that of everything wrought with the Three Rings to fail and fade, resulting in elves having to once again leave Middleearth, that place where they awoke and hold so dear. Hardly can this be called "good versus evil" or either side winning, and if so, it's a phyrric victory for both. Nobody wins in the end; the inevitable is just prolonged yet again through the rise of men at the expense of everyone else. The way Melkor set the stage, Ainur played it, and Sauron finished it, there could never be any victor, good or evil. It was a perfectly balanced system. It was never about Black-White and especially it isn't about good winning in the end, since the victory causes even more tragedy.
But this is, once again, my own subjective opinion and theory. I don't even think there's anything inherently wrong with cosmic good! In general, I wish media would be more willing to take a stand when they choose to display violent acts on television.
I leave LotR feeling terrible pain, loss, and sadness: the main protagonists are forced into exile to another world (planet), Valinor; they can never come back; the fate of the mortal ones (Bilbo, Frodo) will forever remain unknown, they have to forever part with their friends and family, and Middleearth remains behind bereft of elves, their beauty, grace, and intellect. How this is a satisfactory story I am incapable of fathoming, not because any one side won, but because the ending raises even more questions than it answers.
Gandalf being sent back ("I was sent back") is an act of keeping the events in balance, not Eru intervening so that good would win, because in the end, even with him doing as much as he did, everybody loses. Gandalf knew this full well, and that is why he did not want to go to Middleearth. He was afraid. He did not want to go stop Sauron. Manwe ordered him and the other four Istari to go anyway and the other Valar backed him up in his decision.
Even if you take the position that Eru intervened, there is always that moment when Eru Illuvatar tells Melkor "know that nothing you do will ever be without my will and intent of you doing it".
From what I heard Wheel of time is similarly awesome, but no first hand experience with it yet.
However Wheel is mostly great for its broad (epic) scope of the central conflict and how this is told threw characters.