As far as I am concerned, most of the airdrop tokens do not normally have value in the market hence, I will prefer to sell them immediately. I can't hold airdrop tokens for long. The moment I get my airdrop tokens, I will quickly sell it at whatever price the listing of it comes with. I focus less on airdrops but focus much on bounty. As a matter of fact, there were times I have been given airdrop tokens that are not listed in the market at all. So for this reason, if I get tokens from airdrop, I will sell immediately it is listed.
It is your own choice that what you want to do, but i think that first you need to study about the market and want the coin nature once it beome listed in market and after that should take a decision. in fact some time a coin after adding in an exchange do not perform well but later one the price start increasing because of the increasing interest of the people.