I think Stephen Sondheim has written the most beautiful, imaginative, unusual and complex musicals of the 20th/21st Century.

As far as sheer technique goes, Sondheim is head and shoulders above both his contemporaries and his predecessors. As an art form the musical has been on a downward spiral since the sixties though, so Sondheim has had virtually no real artistic competition for several decades. "Hair" was pretty much the last worthy non-Sondheim musical. In the old days there were, among other great writers, Jerome Kern, George Gershwin, Oscar Hammerstein, Richard Rodgers, and Lerner and Loewe--and "My Fair Lady", although not as musically and lyrically intricate, can be favorably compared to "A Little Night Music", I think. Most of the works of Lloyd Webber and Schwartz, on the other hand, are excruciatingly awful.

Andrew Lloyd Webber. DUH!