I have joined so many bounty campaigns but found nothing. Only those give me some bounty which i cannot exchange. can somebody please suggest me any valid airdrop or bounty campaign which you think really worth our efforts. 
No one can give you out but somehow anyone can give your recommendations but still it would depend on your own risk yet finding legit projects wont really be that easy. This is the risk on being a bounty hunter which theres no assurance that you would able get tokens that would really have value.So this do looks like also a gamble.