I use EndNote X which plugs rather nicely into MS Word. Personally, I think it's brilliant as I can manage my entire reading list in the software and print off lists of articles I need to go and get from the library. You can also write notes for each reference which I use to write a few words on why I'm using this reference. Obviously, there's the straightforward stuff of it automatically generating your bibliography as you cite articles in your text.
That said, I haven't seen any of the others, but I consider this a godsend because it keeps my reading tightly organised.