Picking Mozart or Bach would undoubtedly give me a vast amount of unique music, especially when compared to, say, the 5-album discography of a pop artist. However, prolific composers such as these have a tendency to re-use melodies/themes, and stylistically the music will be very similar. Yes, Bach composed a unique cantata for each week of the year, but ultimately they are all derived from the same basic formulas.
Overall, I would either say Beethoven, Led Zeppelin, or Earth, Wind and Fire. Slight contrast, but hey, individual tastes xD