If you are good in trading, then trade, because it can bring a lot of profit. I cannot trade at all, so I prefer to buy a promising coin and to hold it till the better times. In my opinion it is less risky and more profitable.
The risk is indeed low if you buy for the long term. But in this case, one thing to pay attention to is what coins you want to buy and for you to store for a long time. If the coin has no potential or a newborn coin, it will have a high risk. Unless you buy coins that are good and potential, it is a good thing for long-term investment.