The price value, if your going to invest on altcoin you shod be shoo closing coins that has many holders, coins that has many uses, coins that is making progress everyday and most of all the coins is on top 100 coins that are always involve on topic aside from top 100 on the exchange list.
That matters a lot but there is another simple way of choosing altcoin. We all know that these coins highly rely on bitcoin. It is not possible for them to gain value without help of crypto king. If an altcoin behaves exactly the same way BTC does, it means that coin is going to survive at least. In order to know potential of any coin, to what extent it changes value according to BTC should be noticed.