Bounty Suite, created by the people behind Token Suite and Token Drops.
Note: I am not promoting their platform in a any way. I'm a campaign manager myself and I find it interesting to actually see a bounty platform that has an active spreadsheets that is open for anyone else to see.
They state the start dates and end dates of the bounty campaign within their platform as well as how many tokens/coins were in the bounty pool. For me, those are great features that any bounty platform should and definitely have. One last thing they need now is an official escrow. If they can find/hire an escrow to all of their campaigns, it would be great.