I am sure that Alla Pugacheva is the most written and talked about. Why do you think it is so? First of all, she is a talented actress and a really hard-working person: it is not just that she performs her songs - she also takes an active part in creating her songs, music, poetry. While singing she has an interaction with the audience, which she always talks to and send messages. Second af all, Alla Pugacheva has got a charisma which is necessary for modern pop-stars to survive in show business.
Once she said that if she hadn't become a singer, she would have been a pianist.