The best fantasy is deeply religious. The only proof I can offer and still get to church in time is the endurance of Lord of the Rings and its untouched primacy over all other Fantasy. If Tolkien is ever unseated from the Throne of Fantasy, it will be by a deeply religious author, and probably a Roman Catholic at that.
Thus, the best fantasy will tend to reveal the faith of the place and time that produced it. Lord of the Rings is soaked in Roman Catholicism. Narnia is faithful Anglicanism. And they are both very English works.
So what is the American fantasy? The Wheel of Time tried to be. Perhaps it succeeded, though if so it really only succeeded to be the fantasy of the American South (which I do not regard with wholehearted disdain). The religion of the Wheel of Time very much captures the public’s distrust of organized religion.
I would contend that the great American fantasy, our answer to Lord of the Rings, is Star Wars. Despite it’s being set a “long time ago”, it nicely captures the way Americans look to the future where the Old World labors under the weight of the past. It’s zero-to-hero path, where the farm boy becomes the Jedi, captures American concepts of mobility when contrasted with LotR’s zero-saves-the-world-because-of-his-zeroness English aesthetic.
More importantly, and to a degree more indictingly, its hodge-podge of vague mysticism with a dash of redemption at the end very nicely sums up American Christianity.
Of course, once you slap on the prequels, it shifts away from its foundation, and with the extended universe abandons it all together. Far be it from our elites to endorse their enemy. American Christianity may have lost most of its teeth, but the six that remain can still remove the occasional finger.