I'm listening on headphones, they both cruise along really nicely but not really memorable.
Dnb one sounds really good at some parts, most of it sounds fairly average or just not that interesting, the vocals seem to slow down the overall mix too (the parts when its just the bass guitar and drums sounds really clean) some of the effects don't fit, I would love to hear an instrumental with more creative bass and drums. (Hence Drum & Bass)
Dubstep one gets good when the main vocals are gone, enjoyed the nice vocal chop when bass kicks in. Also I think more drums or just more punchy samples (snare sounds a bit flat but that could be my headphones)