As for me, choosing a bounty is the same serious question as choosing the ico to join.
You should do good research to find a worthy program and the project who will in the end fulfill all obligations.

And regarding hodling or selling immediately after the bounty ends - I think the better way is to wait when the project will reach a certain step in its development and become more valuable on the market. And also you can always use these tokens to get access to the projects's functions.