I will not really conclude that one is more profitable than others, it all depends on season and the efficacy of the project. I have both participated in airdrops and social media bounty very well. During the time when ICOs are still good, aidrops can make you minimally rich within a short period of time, I'm talking of middle and early 2017. However nowadays, it's only a few airdrops that comes with the project that someone can get small returns from, many airdrops are shit now, you will even get some of them, 1 or 2 years nowhere to be found on any exchange. In the other hand, social media bounties can pay if you jam the luck or found a very good project. So to me, both of them have the time when they are good.