To my mind, the great French composer Albert Roussel (1869-1937) is one of the most unjustly neglected composers. He has been undeservedly overshadowed by his contemporaries Debussy and Ravel.
His music is vastly different from theirs,and he is not really an impressionist composer,although his music is very colorful. Roussel is a difficult composer to pigeonhole as to style; he neither started nor followed any isms,but remained his own man.
His rugged,harmonically pungent music is invigorating,not elegant and precious like that of his countrymen. There is a kind of almost peasant earthiness to it.
His output includes four symphonies,of which the third is the best known,though the others deserve to be heard more often, the ballet scores "The Spider's Feast" and "Bacchus &Ariane, the Suite in F for orchestra, the exotic opera/ballet "Padmavati",set in Moghul occupied India, the orchestral and choral work "Evocations",inspired by his visit to the great ancient temples of Indochina, concertos for piano and cello and other little-known works which you should find quite intriguing.
Padmavati ,premiered in Paris in 1923,ranks with the greatest of French operas, and is a fantastically colorful ,original and exotic opera which has been revived on rare occaisions; it was revived in Paris two years ago to great acclaim . Do not miss the great EMI recording with Marilyn Horne,Nicolai Gedda and Jose Van Dam conducted by Michel Plasson.
Although his music is not heard live very often,there are a fair number of excellent recordings of his music. The symphonies have been recorded by such eminent conductors as Jean Martinon(a pupil) ,Ernest Ansermet, Christoph Eschenbach, Charles Dutoit,Charles Munch, Marek Janowski , Boulez and Bernstein, and others.
Unfortunately,Roussel's music may never become as popular as that of his French contemporaries.Perhaps it is an aquired taste. But it's a taste worth aquiring.