In aidrop , it is the easiest way to earn tokens but at the same time the value is small and airdrops are goving only small amount of tokens and sometimes those projects that are giving airdrops, stopped before starting the ICO while bounties for me is worth joining for, it takes time but they are paying you big plus it has a chance that their project will become successful , if it will happen the tokens that they are paying you will have a bigger value too. so for me even If I spend time and effort , I wikl go for bounties.