'59 to '64? What's your passion in that five year period? There was the Poulenc Gloria, Shostakovich wrote the first cello concerto, Kodaly wrote his only symphony, Walton his second, Ligeti wrote Atmospheres, Shostakovich the Babi Yar symphony, Bernstein came out with Kaddish symphony. There was so much more - works by W. Schuman, Sessions, Stockhausen, Diamond, Henze and so many others. And so little of it is known, played or even recorded.
I voted 1875-1899. All the symphonies of Brahms, most of Tchaikovsky and Dvorak. The early Mahler and the best Bruckner. The Russian Nationalists in full bloom. An enormous part of the standard repertoire came from these 25 years.