Effective in terms of what bro? in terms of profits? If it is then I would say you should pick bounty, as it has high bounty allocation as opposed to airdrops. Also there are more scams with airdrops, so it is a better way to spend time with bounty.
Therefore it is a more efficient way to join bounty in terms of profits and time spent.
Yeah, it i a little confusing as to what terms would it be effective?
But anyway, I believe to whatever positive aspect campaigns have, bounty will always have the upper hand.
There are a lot of bad news that goes around with Airdrops, hence, all the more reason that bounty is most preferred.