I think you should not believe on airdrop, 99% airdrop campaigns are valueless. And only 1% can bring you good payoff, so how can you choose the right airdrop to join? The answer is your luck, if you dont want depend on your luck? Then you have to do hundred of airdrop per day to get a chance that you will receive good coins. Good luck.
I quite agree with you. Even though I don't really remember the last time I joined in any airdrop, I believe most of them are really valueless so I wouldn't want to involve my time in something that wouldn't really pay much, even some Bounties these days are becoming less valuable talkless airdrops.