I don't have experience of any of these, jaded, but the butterfly one looks a bit too cheap to me (you never know but it looks like a 'risky' buy).
There's plenty of chat about the Vivitar in the DP Review forums
http://www.dpreview.com/ which is a reliable source of info. Just put Vivitar 383 in the search box. On a quick glance the views seem to vary between enthusiastic and luke warm. People say it works much as a Nikon SB 600 which can't be a bad thing.