The reality at the moment is that 2018 is a dark year for the cryptocurrency and altcoins markets. Although altcoins, as well as ICO in 2018 but many of those altcoins, are spam only. Thus, the safest cryptos to invest in 2018 can just be Bitcoin (BTC) and Ethereum (ETH).
I believe Liecoin is one of the most promising coins for the future. Litecoin network has virtually zero commissions and allows you to send and receive payments at a rate 5 times faster than Bitcoin.