70's was a greatest rock decade because it was a time when rised up up amazing British and American musicians: Jethro Tull, Van Der Graaf, Groundhogs, Led Zeppelin, Deep Purple, Black Sabbath, Uriah Heep, Yes, Queen, Slade, Frank Zappa (his best albums are in 70's), Kansas, Pavlov's Dog, Ten Years After, Alice Cooper, etc., etc. And because it was a time when was formed and rised up all the main rock styles: hard rock, art rock, folk rock, punk rock, heavy metal rock... 80's nd 90's was just an afterwords to this great decade. And in 1994 rock was died. Now we seen his afterlife. There are some interesting bands in our time, but they are not consists the rock as a whole. The spirit of rock was lost. IMHO, of couse.