Better to hold that coin if the value is very low. It's value takes time to increase and that is the time to sell it. But if your coin has high value now. Better to sell it than losing profit.
This is not the time to sell any cryptocurrency as it is very cheap now. wait at least for this winter. As for me, I am planning to hold my altcoins (NEO, Komodo, and Lisk) for at least 1 year more.