I would like to think that it's Sara Peretsky. However, there so many others that could hold that title. She is my choice for now. And the runner up would be, in my opinion, Janet Evanovich. Following closely behind her would be Sue Grafton. I have read them all and others. Sara came out on top for me. I will always think that all the mentioned authors above and many unknown others are really exceptional writers in their own right.