The market for altcoins is unpredictable. Some changes so rapidly like when it did happen that ethereum had fallen so fast and that many lost their money about half or perhaps more than. It was doing good but suddenly everything went upside down. And the good coin becomes almost as worse as nobody had ever thought about the sudden decrease.. So to choose the best coin, I think it would be appropriate to check their current condition in terms of price and the volume to identify and analyze movements of alts. Don't forget to check current issues as well because it also affects the prices of the digital coins.