Arnold Schöenberg said that music should be true. I definately think there is something to this. Concerning differences in taste, i think one aspect of it is differences in how people appreciate different emotions/moods - a difference in personality, or a difference in experiences. Some
people may be drawn to sorrowful moods, while others may have difficulties relating to sorrowful
moods because it reminds them of f.ex. loosing a family member. Furthermore, some emotions are considered more noble than others - compassion is nobler than jealousy. So i would say that the music that resonates the strongest emotionally is music that expresses emotionally what is truly humane.
People write music inspired by litterature and art, therefore there is something to music that isn't solely
determined by music theory. For instance the climax around 5 minutes into the 3rd movement of Debussy's string quartet reminds me of Victor Hugo's les miserables, which to me is very noble.
Another thing is what Morton Feldman called "organic continuity", a natural flow of the elements contained in the music. (Good music would be organically flowing) Also, i think of the "rhetoric" of musical phrases. Bad music contains a shallow kind of obvious tonal motion, variation/imitation. Don't know if i managed to communicate my perceptions well, but hopefully it could stimulate some thought.