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
But its budget is very low. According to my observations, they only spend about 10k $ for their entire airdrop, so surely each person will receive a few cents for each time they join.