Beethoven, Tchaikovsky, Mozart, John Williams, Hans Zimmer, Wagner, Nobuo Uematsu, Koji Kondo, and Yoko Kanno. Kanno-sama is a music composing goddess.
My top favourite composers live all in the Baroque Era and are J. J. Quantz (my dear husband xD), G. P. Telemann, G. F. Händel, J. S. Bach and A. Vivaldi.
I also like O. de Lassus (from renaissance) and all the compositions of the School of Notre Dame.
Bach, Beethoven, Dvorak, Tchaikovsky, Chopin, Mozart, Brahms, Strauss, Schubert, Satie, Pachelbel, Albinoni, and a lot more that I can't think of right now.