Off the cuff, Marasi Colms.
Not to say I don't like her as a character (I'd probably hang out with her), but her academic exposition pulls me out of the story for a second.
Mistborn was the first I read, so it holds a special place for me, but my favorite Sanderson book is definitely Warbreaker, and is in my top five books (the others being from the Belgariad/Mallorean and Oathbringer).