The problem these days is again just the sheer amount of music available, and that music isn't as important an experience in people's lives in the 21… - Andrew Sega

If anything I probably gravitate to things with great melodies/harmonies, and interesting/syncopated beats.

A human is a complicated organic/electrical system, which is immersed in a culture. Try raising a monkey like a human, it won't work, you need the human's certain brain characteristics (including self-reflection) in order to create a truly intelligent creature. The brain processes inputs and perception in very particular ways, and I think until we understand the underlying processes better, there is no way to really simulate it in software. Computers will continue to be good at simplistic analysis, and raw processing power, but the subtlety of emotions is something intrinsic to the human organism and culture.

I think there are some objective [musical] qualities... how complex something is, how melodic, how diverse the tonality is, et cetera. But I could also make a piece of music that contains all of those and yet isn't "good" from a subjective viewpoint. For example, take Beethoven's "Moonlight Sonata", Beatles "Yesterday", and Underworld's "Born Slippy", and play them all on top of each other at the same time. Great music in their own right, but terrible sounding together.