Though you have point out some banners but there are also some most important issues to choose a best bounty program. Those are-
1. Topic
2. Token allocation.
3. Road map
4. Management team
5. Escrow that is very vital factor investors.
6. Time period of bounty.

etc.. are also may be vital factor to choose a good bounty and which bounty will scam that actually could not said before bounty running.