At the moment it seems that only a few airdrops are worth following,
so most likely we will just waste time and better not have high expectations of airdrops,
I personally would prefer to join the signature campaign and it's more profitable too
Not all of them can also be profitable even though it is around signature campaigns, because it still depends on the success of the project that created the campaign (including signatures) because this year and last year there were also signature campaigns that did not pay after the duration of the campaign was over.
Not all of them really are profitable because some of those just try to scam people that's why its good that we are vigilant upon choosing airdrop and we make sure that they didn't require any deposit before us to withdraw their given share to the people. We can choose many free and there's a simple task to be done so I guess we can choose these then join all of them until we spot the potential gem which can give us profit. On signature campaign which pays bounty tokens? I can say its the same and we need to spend a lot of time waiting if we get paid and if not all of our efforts completing the task for many months will go wasted.