The bounty is a good marketing move. That it is possible to think up better. And this despite the fact that to pay tokens and not real money.
Airdrop can cause interest to the token but not always to the project. Bounty can be diverse.
It seems like recently, advertising on social networks like facebook or twitter is not very effective. I generally appreciate those projects on reddit.
The best advertising of the project is a ready-made good MVP or a fully functional product.

Just words investors do not trust))