A well decentralized Altcoin and plans to improve the coin decentralization in the future could make me hold an Altcoin long-term. I cannot build a permanent base on project that is not truly decentralized.
I will also consider the coin Roadmap, expansion plans, developer's enthusiasm, project long-term viability, concepts, strategies to capture millions of users, etc.
Developers ideals matter most in the end. .
The characteristics of the altcoin and the roadmap is very essential in knowing a better altcoins specially the products and services that they introducing is it viable and also the sustainability for the future that it would last longer and the value of the coins will not drop after launch.