Jethro Tull

Perfect in Blues, Jazz, and Folk with This Was (which is very, veeeery Jazz! Listen to it all very attentively!) and Stand Up; in Hard Rock with Aqualung and War Child and in Prog with Benefit, A Passion Play, Living In The Past, and especially Thick As A Brick, which for me is the archetypal Prog composition. An absolute genius as a flutist and Folk guitarist, and two extraordinary and ABSOLUTELY underrated lead guitarists (Abrahams first, then Barre). Is that enough? No, there are also the lyrics. Sublime.