I'm a "sometimes" kind of listener. I'd say my favorite acts are KOS, Sound Assembly, Faithless. Mainstream hip hop, I've always loved the Beastie Boys and dig the sound of 50 Cent's voice. Not much for Gangsta Rap, though NWA did have its time with me.
Edit: I'm a complete neophyte in the various hip-hop genre's but wouldn't mind a tutorial.
I wouldn't call myself an expert either, over the years I've heard of the usual big names: Jay-Z, Nas, Notorious B.I.G., Outkast, etc. Then something happened in the past couple years and I started to get heavily into R&B, Soul, and Hip-Hop (I guess I got tired of listening to Bob Dylan, Velvet Underground, and their re-incarnations). For a while I had a handful of albums on my iPod, then one day I had the bright idea to look up a 'greatest hip-hop artists of all time' list. I ended up downloading and checking out a huge number of different artists and found what I like.
Turns out that a lot of the good hip-hop artists actually seem to be the big names, which stands in contrast to the indie scene (unless there's a whole amazing underground scene I'm missing out on). Anyway, I'm not familiar with any hip-hop sub-genres, but if you want to check out some good, recent artists, try Kendrick Lamar, Schoolboy Q, and Danny Brown, Kendrick being the biggest name of the three.