My favorite female author is Barbara Kingsolver. Her books are funny, touching, and I love the way she effortlessly weaves information into her plots so you learn something as you read, almost without even realizing it. So far I've learned about coyotes, entomology, astrology, and Native American culture from her books.
My second favorite is Tabitha King, wife of that guy who writes horror stories. ;-) Her characterization is amazing. I don't always like her characters--especially the women--and I've been known to throw the book across the room as I'm reading because they make me so mad, but they definitely make a lasting impression on me, and I care about what happens to them.