If you love Dark Souls you owe it to yourself to try Demon's. I'd say Dark was better in pretty much every respect although I'm not going into why as it's been discussed in both this thread and the Demon's one (and I mean a discussion, not an argument, these games always bring the best out of people for some reason!).
The reminds me, i've gotta get the soundtracks ripped to my phone. I love the Nexus music so much