I think that you can name a few bounty managers, but these people are not so many. I think that among the trusted ones I can call Sylon and hua_hui, other bounty managers have problems, but this is just my opinion on this score so do not judge my thoughts strictly, because they are only mine.
In here are a lot of good bounty managers that I am participating right now like yahoo, Sylon, deadly and many more. I assure these are the legit to participate from different campaigns.