I've got stuff on both. I'm still kind of in a testing period. I don't get a lot of views on either by search/chance, so most of my views are generated from embeds, which works with either. For the time being, I've decided on using YT for tuts and misc stuff, and using vimeo for finished pieces, because it looks more professional and then I have a more polished set of videos. I just feel like those fit the respective communities better. I should upload my finished pieces to youtube too.

The downside to vimeo for finished work is embeds don't allow HD unless you're a pro member.

Random: I did record a very crappy tut on ncloth for a member on this site which currently has over 4000 views, pretty much everything else is under 200. Why does the crappiest thing get way more views... and I can't even delete it, because what if someone decides to watch something decent on my channel because he found the crappy ncloth demo.