Brandon Sanderson! *swoon* My favorite is The Way of Kings, but Elantris, Warbreaker, and The Mistborn trilogy + The Alloy of Law are all amazing too!
I can't quite get through The Wheel of Time series. They're vastly overrated in my opinion. I got through the first two books, and I will probably force myself to read all of them just because I'm a huge Brandon Sanderson fan and want to read all his books. The biggest problem I have with them is 1. They're overly predictable. and 2. All the main characters are whiny brats.
Before my Brandon Sanderson obsession, my favorite book series was the Knights of the Round Table stuff by Gerald Morris--my favorite book surprisingly being book 4, Parsifal's Page.
No mention of the Bartimaeus trilogy + the prequel by Jonathan Stroud? I swear, they must have only been popular at my school or something. The main character Bartimaeus is hilarious, and I think this book series is the perfect mix of humor and darkness that's really hard to duplicate. I think even the author has failed to comprehend and duplicate the brilliance of the character Bartimaeus, which is why he then wrote a prequel that doesn't entirely make sense but still amazing, while his other books are dull and drags on and on.
I just recently read Mortal Coils and the sequel All that Lives Must Die. As you can imagine, they're pretty dark and it's a book series that really questions what's right and what's wrong. Is duty more important or is warmth and caring? Do you kill one to save another? Do you kill many to save your loved one? Do you let someone die for the good of all? All the characters are really realistic, sometimes so complex and multifaceted that they feel...hyper real.
For something lighter, I love the Erec Rex series by Kaza Kingsley. I personally like this series better than Harry Potter because the characters are slightly more flawed and the tone stays consistent throughout the different books.