Well, I would go to Ethereum because experts believed that this cryptocurrency may overtake bitcoin market cap in the near future where it had made a 40 times growth rate in just 2 years. It's platform permits creating a bright contract that runs on a decentralized network and runs precisely as programmed without any chance of downtime, deceit and third party interface. Next best atcoin for me would be Steem because it has a very fast transaction speed of only 3 seconds and it has a zero fees. This currency is now being used in Steemit, a social media cum blogging platform that awards the satisfied creators.