Fantasy as a genre is often unfairly wronged. While there are plenty of authors who seem to be paid by the word and are only concerned with expanding volume, there are many authors producing fantastic works that are worthy of the word literature. While there were many worthy competitors, here are what we consider to be the great work of the greatest fantasy series of all time.
①The Dark Tower by Stephen King
The Dark Tower actually shares some similarities with The Wheel of Time. In both series the first four books are the strongest, and you also get the sense with both Robert Jordan and Stephen King that they didn't quite know how to end their creation, which led to a very controversial ending in The Dark Tower's case along with some questionable decisions by King like his self-insertion in the story.
King has created one of the most iconic fantasy characters of all time in the Gunslinger Roland and the world he creates, with all of its similarities to our reality, is a prosperous one. It's too bad that Stephen King doesn't dabble(涉猎) more in fantasy, because he clearly has a talent for world building. Not to mention everything he writes seems to be phone book sized, which would fit right in with the fantasy genre.
②Harry Potter by J.K. Rowling
When considering a ranking of the greatest fantasy series of all time, the question of Harry Potter is a tricky one. There's inevitably opposition when something is as popular as Rowling's work, and add to that the fact that the series is seemingly meant for children and you have a case that naturally inspires a lot of debate. I'm not sure I believe Rowling did anything particularly new with Harry Potter, but a work doesn't necessarily have to be innovative for it to be great. Nearly every fantasy series owes a debt to Tolkien for instance, but that doesn't mean Tolkien has written the only work of fantasy that matters. Rowling didn't really come up with anything new, but the connection she made with tens of millions of readers is praiseworthy. People will be reading Harry Potter for decades to come, and I'm not sure a better introduction to fantasy could be found.