K, I will say that WoT was the best at epic fantasy until RJ let the series slide so badly in books 7-10. As at book 6, 15 years ago I would have agreed with you. However, fantasy has grown so much since then, that RJ lost that title for me a long time ago. This being said, WoT has come back from the edge of the abyss with the last three books, and Sanderson is doing a fine job of bringing it home.
Right now, in terms of great big sprawling multi-volume epic fantasy, there are three shining stars:
Far and away the most popular is George R.R. Martin's A Song of Ice and Fire, which is very, very different from WoT. The fantastical elements (except for dragons) are more in the background, and political intrigue is absolutely huge. It is extremely dark and grim, and it is fantasy for adults to be sure. No farmboys finding a magical sword, instantly becoming expert swordsmen, and being mentored by kindly old wizards. We have hard-bitten warriors, fighting kings, cynical advisors, cunning, manipulative women in the backrooms and bedrooms, and a story that steadily builds for three of the four published novels, and then slows a bit in the fourth. Excellent characters and unexpected twists dominate the story, which is mainly political, but with plenty of foreshadowing of something big and supernatural building. The big down-side to this series is that GRRM has been writing and re-writing the fifth book for over five years (he is apparently almost finished (but no one is holding their breath)), and he is very easily distracted by things like football, comic and fantasy conventions, and by other projects, such as the forthcoming HBO series of the first book in this series, A Game of Thrones.
The Malazan Book of the Fallen is another huge epic. Steven Erikson and Ian Esselmont (they each created the world, but write their own books in it) have created a hugely complex and sprawling place. You don't begin to start figuring out the over-arching storyline until the end of the third book. It's complexity puts some people off, and it, like ASoIaF, is relentlessly grim, but the polar opposite in terms of magic. The fantastical and the supernatural are elements of daily life, where gods take part in the politics of humans. Erikson in particular is extremely productive, and puts the books out in this series about once a year. It wraps up this coming year with the last volume in the Book of the Fallen (The Crippled God), but other novels are planned as prequels, etc. The sky is the limit, as there are countless stories to be told in that universe.
I consider the best big epic series going is Janny Wurts' Wars of Light and Shadow. Not as dark as Martin or Erikson, this is a massive series that has eight books out, and the ninth is in the final stages of editing. Definite release in 2011. After that, two more books finish the series. Intense plotting and amazing characterization, her series does not suffer from "five-billion POV" curse that seems to plague Jordan and Martin, and to a lesser extent Erikson. The series starts with Curse of the Mistwraith, taking place over 500 years of conflict. You will find by the end of the first book that this is not fantasy lite, but like Erikson and Martin, she is not afraid to hit her readers hard with a grim dose of reality. However, in contrast to them, she tempers the reality with moments of rare beauty and the hope of something better than what has gone before. The themes are strong yet subtle, the characterization is second-to-none (you won't always like them, but they are so darned real), and the plotting is intricate like Martin and Erikson. Her writing style deliberately slows your reading pace down, as she is trying to get you to see things from different perspectives, instead of just entertaining you. There are several different magical systems, and some of the themes are borne out in how they work. Also, music is used as one of the magical systems, which just makes sense to me (it is the closest thing to magic on this planet).
Each of the three I would say are better in just about every respect compared to Jordan (and I was one of the original Jordan fans waaay back in 1990), especially in terms of characterization, tightness of the story, better plotting, and a more mature story line (no omnipotent Dark Lords that somehow get beaten in any of the three (well, kind of not in Malazan, but you can figure that out for yourself when you read it). Jordan is what went before, and he created a stunning series, but with obvious flaws. The three I list above take fantasy to the level of literature.
One further consideration is Sanderson's new series, The Stormlight Archive, starting with The Way of Kings. It is projected to be ten huge books long, and Sanderson is a proven workhorse who writes books quickly. He looks to be something of a Stephen King in the fantasy genre, based on his productivity.
