Melodies.
I didn’t know he composed the lyrics as well, is that right?
I think one of the major effects of music is its ability to “stir up” your emotions that no other medium can do.
To be honest I like all kinds of music. And I guess it depends what mood you want. I like Gregorian chant because it feels sacred and that can fit very well with the sanctity of the Mass. However it never stirs up any emotions inside me to go out and combat the world and giving me courage to live a daily Christian life. Modern music like David Haas is not very sacred and certainly I wouldn’t just sit there and admire its beauty. But it does infuse positive energies, or reflective mood as to how much Christ has done for us and can move me to tears, which chant don’t.
Anyway that’s just my personal experience.