Martha Argerich...do I need to say that again?
I think her technique is one of the most phenomenal ever, male or female. Admittedly, there are fewer women considered as super virtuosos(Argerich being the most famous one). Then we have less famous names like Annie Fischer who can be demonic at times. Lisitsa(some find her phenomenal while others think she is quite sloppy, I am with the latter.)
For example when asked about male supervirtuosos I can immediately think of a dozen of them: Hamelin, Hofmann, Richter, Michelangeli, Pollini, Lhevinne, Barere, Cziffra, Berman, Kissin, Horowitz, Libetta...etc.