Read their whitepaper!
Yeah. That simple. You look at how unique their project is and how the community would benefit from it. Then next is the team behind it which is really important if they're legit or not. And you can add a little bit of extra research about it.
with a coin with an ever-improving development will be great by having it. because with this growing development it will be great to have it. other than that for a good koi is very capable of being a much better and more improved future. so it is great to pick a coin to become a mainstay coin.