Airdrops are definitely scam i prefer bounty because it's safer and you also see your progress in the spreedshit. If team don't pay bounty community begins a big scandal 
in other words "99% of airdrop tokens based on eth blockchain,wave or neo are scams " , in other side 90 % of airdrop coin with independent blockchain are 100 % legal . Do you know why ? eth token are easely created not like other one. Because of what said i prefer airdrop than bounty .