Shelley Gruwell wasn't the "best" female bodybuilder per se but she did fuel many of my adolescent fantasies.
Cory Everson was probably the greatest Ms. Olympia in terms of being a great representative for the sport.
Rachel "Dee-lish" McLish was the first Ms. O and her physique kind of evolved with the nascent sport of professional female bodybuilding--in a good way, back then. At the first Ms. O she was too lean and ripped, almost stringy, but she looked much better over the next few years.