If I can choose a Bounty which can give more return. Have any indicators that can help me to choose a best bounty.
I advise you to follow the bounty that are held by trusted managers. such as the Amazix team, yahoo62278, irfan_pak10 and Aerys2. they are reputable managers. Maybe this is the best solution.
I'll agree here. Just bear in mind that these managers are reputable and trusted but it does not guarantee THEY won't be scammed by the projects they are managing. I personally can see yahoo62278's campaigns are well managed, but those others named are equally good in standing. Of course, I stand by my own manager (BoXXoB).
Whatever it is, don't blindly take what they manage, like the project yourself too.