Of all time?? That's hard. I doubt any of us are experienced enough to answer that, especially if people are suggesting names like Sandra Bullock and Beckinsale. They aren't even in the discussion of our times, let alone of all time. Meryl Streep is the only legit name mentioned in here thus far. But how many of us have seen movies with Audrey or Katherine Hepburn? Marily Monroe? Grace Kelly? I've never, but I know these are highly regarded names. And you really can't say if you've haven't seen their work.
But from what I've seen: Kathy Bates, Meryl Streep, Dianne Keaton, Julia Roberts, Jodie Foster, Sally Field and Susan Surrandon.