I have heard very good things about the classic “Mormonsim” By Jan Shipps. She is a preeminent academic about Mormonism.
The best book I have personally read is “Religion and Sexuality” which isn’t what the title sounds like. It goes into a few religions that have similar beginnings and put them into a historical and cultural context; Mormonism, Society of Friends and other groups. I read it in an anthropology class at BYU that studied familial relationships in their anthropological setting. I read it years ago so I don’t know if it is still in print.