Top 3 altcoin that I believe they are worth to invest long term are: Monero, NEO and Ethereum. Monero is one of the altcoin that I love, it has good technology, no one can hack monero. Every transaction with Monero is completely anonymous, no one can find the information of the sender or recipient. In future Monero will be more popular when the government controls crypto. NEO is altcoin dubbed as Ethereum of China. The highlight of Ethereum is that it's geared toward smart economy and it has faster transaction speed than Ethereum. And finally Ethereum, this is the queen of the market, it has high stability, I believe that in the next few years Ethereum will grow stronger and higher value.