I am a big hip hop fan, and also RnB.
I tend to lose myself in the beat of a song, and much less so the rapping. So if you talk about the difference between straight rap, and then Hip Hop, there is a difference.
But anyone who know's me on PC knows I love my Hip Hop. I think it has developed mainly from being engrossed into the basketball culture. I am always playing and watching the sport, so am generally subjected to the music on a regular basis, and basically fell in love with it.
Mainstream rap/hip hop: I'm not gonna lie, I do like quite a bit of it. I wouldn't call Soulja Boy rap/hip hop at all, but 1 or 2 of his songs are catchy, but he really has given the genre 'Hip Hop' a very bad reputation.
Unfortunately many people listen to 1 Soulja Boy song and instantly think all other hip hop is the same, which any right minded person would know it's actually quite diverse.
Now, the stuff I listen to mainly is what some refer to as 'true' hip hop. I tend to go for artists such as Mos Def, A Tribe Called Quest, The Foreign Exchange, Jurrassic 5 etc, though also go for plenty of new stuff as well. My all-time favourite artist is probably Jay-Z.
This is a song I would refer to as summing up exactly the sort of music I like. The beat and rhythm to this song for me is incredible.
https://www.youtube.com/watch?v=UU2q-r_9GfQ
Obviously it's not to everyone's taste, but to me its like the greatest song of all time.