drop first.

By "type" I don't mean genre tho...

Let me give 3 examples, using 3 songs from the same genre to help
the point.

Exhibit A:
Take "We're All Killaz" by Shock G http://www.youtube.com/watch?v=Gi1AVy49eyA
The music itself doesn't do much for me. The song is even set up
in such a way that his lyrics are what grab your attention before
the music really drops anyway. The lyrics are humorous and thoughtful.
The music is kinda goofy and serves to facilitate that, and it totally works. It's one of my favorite songs. Had the music dropped first
without any lyrics, I might have skipped it or not listened until way later.

Exhibit B:
A song that was just released... "Oil Money Gang" by Rick Ross. https://soundcloud.com/maymaybachmusic/rick-ross-ft-jadakiss-oil
The music drops first and it's already sick as fuck. Ross and Jada's
job is simply to not fuck that up. I'll listen to it just because the
music is that good and the rhymes aren't terrible.

Exhibit C:
"Troy" by Pete Rock & CL Smooth. http://www.youtube.com/watch?v=7wEw05-Ef5Q
This begins with a simple horn loop, then some bass, but CL starts
rapping as soon at the beat drops. His lyrics are immediately
introspective and engaging. I remember hearing this when I was
younger and being just as lost in the story as I was in the music.
This is back when I was much more musically focused than lyrically,
so that was quite a feat.