As a young woman Liz Taylor was truly beautiful. (Hard living spoiled that as she got older.) But If I could spend a night on the town with either one of them I'd choose Monroe. I think she'd be more vivacious, more fun, less self-absorbed. For my generation, Marilyn Monroe was Aphrodite incarnate.
But the final word on age and beauty belongs to Dorothy Parker. She said, "Time is a great healer but a lousy beautician."