Its depend on a project.if it is a good project with fully recommend or with massive potential its better for long term hold. And if it is a hyped one better to flip it and make good profit.but it is not a good recommend project better to short term trading or sell immediately
I agree with this, if you actually do not need the money and the coins you have is a great coin just hold it. It might worth a fortune after a while. Since you do not have any investment on it then you have nothing to lose.