I love Robert Plant, all versions, even though you won't find a more emo sounding fucker out there. He is emo with a hard-on, taken to extremes. Ozzy's cool, too, but I honestly don't see much difference in most of his music, except that he pursued the commercial sound a bit as time went on. I can't blame him too much for that. You have got to play to your audience to survive.
Don't get me wrong ... I'm not a music snob, at all. I like all the bands I just mentioned, even though I seemingly used them as negative examples. I don't really prefer anything different from most folks, just more of it and I have a little wider tickle spot for music, in general.