John, Paul, George, and Ringo were the greatest foursome rock has ever seen by virtually any measure based on anything other than emotion. #1's, albums, range of musical style, original scores and composition.
Bonham, Plant, Page and Jones were definitely a great original metal band and their innovation and style certainly became a mold that many other bands followed including IMHO the aforementioned Iron Maiden where in many of their guitar echoes you can hear the zeppelin influence. LZ 4 is still a favorite
LZ is definitely right up there on the popularity scale but in terms of influence on the evolution of rock music and by any real objective measure the Beatles are by far and away the greatest band.