It depends on your abilities to follow rules and guidelines, most bounties require you to adhere to some rules before you can qualify for the token whereas in airdrop you are likely not to follow any major rules. But most quality token now prefer bounties programmes than during airdrop. Most airdrops now are worthless, and also prone to scam.
Also,  bounties gives you the opportunity of knowing more about the tokens and their programs. To me,  I prefer bounties over airdrops