I find the best thing to do is follow the #airdrop tag on twitter, and just submit to which ones you feel comfortable with. Never pay anything for an airdrop ever, unless it's an extremely unsubstantial amount such as 0.000000002 eth or something.
I follow two twitter bots for airdrops. Which scrapes ANN threads with the #airdrop tag:
https://twitter.com/airdrop_moyashiI can't find the other one in my 600+ following list, damn.
yes the same I also follow the airdrop from twitter that although the results are not comparable I am happy