With no hesitation, I focused on Kurt Weill. If you listen to a thousand pop and rock songs from the past 50 years, you'll hear the influence of Weill not only in the renditions of his tunes but also in the inspiration of his innovative and experimental instrumentation. If you listen to a hundred theatre musicals from the past 50 years, you'll hear the threaded changes that Weill's theatre music provoked beginning with his singular collaboration with Bertolt Brecht. If you listen to contemporary concert music, you will hear and feel the astonishing impact that comes from the body of Weill's symphonies, quartets, nocturnes and lieder.
Kurt Weill lived, exactly, during the first half of the 20th century. When he died in 1950, the distinguished music critic and composer, Virgil Thomson, said this about him:
"He was the most original single workman in the whole musical theater, internationally considered, during the last quarter century... Every work was a new model, a new shape, a new solution to dramatic problems."
For me... that says it all!