There are many factors in which you can choose good bounty campaign, but you have to look only at project hyip, its team and useful and real product ( not fantastic ). Don't look on bounty pool, it doesn't matter.
I think the most important thing is really the team and the product. Just pay attention to the hard cap, if it is too large, it is a reason to think that the team does not know how much they need money, and therefore they have nothing United.