I think bounty hunters earn more compared to airdrop hunters. Airdrop hunters is just once, till the day of distribution of the tokens(except you wanna do something illegal to the rules, then you can earn more), but bounty hunters work till the end of the project and are being paid weekly till campaign ends. And what if the bounty hunters work with all (i.e Facebook, twitter, LinkedIn, signature etc), you'll get a bigger pay at the end of the project's campaign.