I liked Legion too, but was trying to limit how many Sanderson books I recommend
The Stormlight Archive is definitely his winning book at the moment, if he keeps up the pace. But Mistborn Trilogy and The Alloy of Law are incredible too.
My friend Jim just had the first of his six book series published. It's called Forged in Death, and it's really really awesome.
Also. THE SERIES IS ALREADY COMPLETE! lol. The publisher will be releasing them in 6 month intervals from what I understand, so you won't have to wait forever for him to finish them. I've read them all (buahahaha) and they're definitely worth it.
Neil Gaiman's work if you haven't although it's not a series. He uses a lot of the same motifs in his work. For any sci-fi/fantasy fan, I think he's a must read.
A bit late in this thread, but you should totally try Kushiel's Legacy by Jacqueline Carey!! The first book is Kushiel's Dart. Amazing, amazing series, now tied with Outlander for my all-time favourite...