Let me just admit first that I am not a huge music buff. However, I can't help but make this weird observation.
Is it just me or do a lot of proponents and fans of sacred music seem to confuse what is good music with what is simply suitable music for a certain context?
Now don't get me wrong. I don't really care (generally) so much for what kind of songs are played in Mass. If your church plays more modern Christian music, fine. If you insist on traditional polyphony, organ, or Gregorian chant, that's fine too.
However, with regards to the latter, if you're going to start saying that music like that is the best music and even go as far as to say it's should be the only type of music Catholics should listen to, then we're going to have some problems.
Contrary to what some of you might think though, I personally don't believe there really is a "best" type of music out there. For me, I find it all boils down to taste (and whose taste gets publicized and popularized).
That's not saying that certain types of music aren't more suitable in some context than others. That's why I'm saying that if you believe Sacred Music is the best for the Mass, then you're probably right. It is suitable in the context of religious worship.
That doesn't mean though that it is the BEST music out there.