Most of the modern American mainstream rap sub-genres are garbage (crunk and snap in particular). As previously stated, the older stuff was good, but somewhere along the lines, it became about whats marketable and what makes the most money. While such a thing is understandable, much like pop music, it suddenly becomes quantity over quality, and the result is the horrid acts like Soulja Boi. Oddly enough, it seems that some modern American mainstream rap is taking a step backwards: many songs contain more electronic elements than before (so much so that the other day my neighbor, a 20 something black male, had his car stereo very high and his subwoofers turned all the way up, and I heard a song that had a sampling from a house song called "Destination Calabria", and that song is several years old), as if they're trying to go back to that "old school" sound of the 80s.
The non-USA scene is slightly better from what I have heard, though my experience with said scene is very limited.
The odd, more underground rap sub-genres such as Nerdcore are interesting, though I have little interest in such things, because while I am capable of relating on the topics presented in the music, I really don't want to hear people rap about it.
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