Most of you have suggested me to check the usefulness of the coin. To be honest, I can't see any this type of coin in the market other than Bitcoin and ETH. Probably I am not yet known with all of the useful coin.
What is the usefullness of bitcoin, to be exactly? I can give you some example of good altcoin. Hope you can find your own method to indentify them:
- BAT: real solid working product (Brave browser)
- BNB: same as above. it's backed by the world's largest crypto exchange
- XMR, ZEC, Dash: a lot of people like anonymity. this makes these coins valuable
...
There are a numerous factors but usage of a coin is one of them. You should also check the dev team and community of that coin.