i will never forget the best airdrop that ever was , i think that it was 2013/2014 , there was an thread that announced the new coin , build from scratch , you only had to send an email and you participated in the airdrop , if you did that you would have recieved 3000.000 XEM (NEM) , it is still worth something
best airdrop i've seen is ludena protocol. its a top tier coin listing on bithumb or upbit probably very soonand giving a chance for people to get free tokens now
Since 2017, I have seen a lot of airdrops with good budgets. Even if each person received $ 3-5k from an airdrop that is Hydro, it is definitely the best airdrop and makes many people rich.