It is very difficult or let's say not easy to easily said that one campaign is better than the other, but well! you can check some markers to determine whether such campaign will be successful or not. First of all I check the project idea. That is very important to me, any investor will invest in a project that is interesting. You should also look out for the developers of such a token or particular project. That is very important, check how many times they show their faces, and also whether their credentialing and background is valid as they stated. I also love working with bounty managers with good portfolios. I know some managers that most of their bounties that i joined went on very well. To end with, I also look out for a large community backing, but the question is what if you joined early. So I stay in for a while(about half of the whole bounty duration), and if the project still does not get followers and early adopters I then start to think twice. This is because whatever bounty you conduct will survive on a larger community backing.