I have answered this question so many times, I decided to dedicate a web site to answer this question. Here it is:
http://www.life-after-harry-potter.com
Included is a list of only the best sorcery fantasy books, grade reading level, a short review of each book along with a brief summary of adult content. There is also a "Readers' Choice" list of favorite books, and a list of heroine sorcery fantasy books, plus a brand-new original fan fiction.
Andre Norton is probably *the* classic scifi author. However, most of her main characters are male - as nearly all of her audience was male throughout most of her career. Indeed, that is why she chose a male nome de plume. However, her story "Moon Called" (one of her later stories) is quite good and stars a young woman.
My favorite female-main-character scifi/fantasy is "The Harperhall Trilogy" by Anne McCaffrey. The main character is without a doubt my favorite female main character. However, these books tend to be male-oriented, particularly the earlier books (two books precede this trilogy), in which men kidnap, dominate and rape the women - and the women like it that way. However, in the "Harperhall Trilogy", the main character manages to avoid such treatment.
My favorite female-authored fantasy books are probably the Deryni books by Katherine Kurtz. Although these, too, display a male-dominated storyline, women frequently play strong and significant roles, particularly in the "Camber of Culdi" trilogy. Kurtz's books are medieval and Christianity is pervasive throughout (as it was in that era). Though I find that this pervasive Christianity (based loosely on the Anglican Church) adds realism to the stories, some might be offended by such prevalent and overt Christianity.
The "Thieves' World" anthology includes many female writers with female main characters. It may be instructive in furthering your search for fine female authors of female-starring fantasy to read this book, as nearly all of the stories are very good to excellent.
Bradley's "Mists of Avalon" series is generally well-liked and considers the Arthurian cycle from the point of view of Morgan le Fay. However, I found this first book - which is supposed to be the best - quite disappointing. Perhaps in order to strengthen the main character, Lancelot is portrayed as a homosexual and Arthur as a bisexual. Nearly every character has some significant sexual behavior disorder of one sort or another (starting at its most mild with the incest between Arthur and Morgan as youngsters). In general, I felt it inserted *far* too many problems into the lives of characters who already have so many problems to deal with in existing legend that there seems no reasonable purpose in making *everyone* a basket case on top of it all.
I hope this helps.
Jim, http://www.jimpettis.com/wheel/