Looking at this benchmark website here. (harddrivebenchmark.net)
You can search for each of the drives. The samsung spinpoint is ranked higher than the other two. I've heard lots of good reviews for it, but not actual hands on experience myself. I do have one sitting in my room in its packaging though, you can get it for $65 from here. (Ewiz)
As for the WD Black drive, it's nice and has the new 6 Gbit/s transfer rate (Although apparently mechanical drives can't use that much anyway), but I personally don't think its worth the extra $30 I would have to pay on newegg. I don't know much about the barracuda though.