In determining the best cryptocurrency for long-term investment, I strongly consider four factors. First, I look into the versatility of the coin's use cases. Those with broader applications usually prove more resilient. Secondly, I examine the industry partnerships in place. Partnerships can significantly thunderbolt a cryptocurrency's legitimacy and use. Thirdly, I assess the coin’s network security. A robust security framework is critical to prevent any potential cyber-attacks. Lastly, the growth potential in relation to the circulating and maximum supply is key. This tells me there's room for growth and scarcity which drives demand.