there are a lot of platform in the bounty hunter but If I can give you a recommend I think I will give you my favourite bounty management not bounty platform, they called amazix team, and I think they have a lot of success project, not all of the project success but the percentage of success from them is high
Yes they are very professional. I've been doing bounty campaigns with them for some time. I would also recommend are Bounty0x. They are still in beta though but there are many bounties there for anyone (including newbies) to participate in.