Most airdrops are just waste of time. Although i cannot deny the fact that there are good ones and sometimes you may not be able to tell when you hit a good airdrop that will bring you big profit. I have seen and participated in good airdrops as well as scam airdrops. That is why i do not attach much importance to airdrop again. I prefer bounty.
Depands - the ontology newsletter airdrop was quite nice