Who was the most creative rock artist in the seventies?

What music craze of the 1970s replaced the rock n roll music of the 1960s?

Rock music wasn't replaced by anything. Not in the seventies, nor in any decade after the seventies either. It changes and evolves, but it's never disappeared. The sixties was the era of protest songs and psychedelic rock music. In the seventies, rock music split into a few different styles: glam rock like KISS and Alice Cooper, punk rock like the Ramones and the New York Dolls, and I guess what you'd call "classic rock," like Led Zeppelin, Deep Purple, Pink Floyd, Lynryrd Skynyrd, who continued playing that sort of psychedelic, long-winded, elaborate rock music. The seventies was also the era of disco, but disco and rock music have always been incompatible with each other. Traditionally, rockers hated disco people, and disco people hated rockers. Disco music was sort of the seventies equivalent of the bubblegum pop music of the fifties and sixties. It was popular music, by the most literal definition of the word. It was the kind of music most American young people liked and danced to. Whereas all forms of rock music have traditionally been the rebellious music of the counterculture, disco was the music of the regular culture, the non-counterculture.