I can suggest more than such best coins which are currently undervalue but in coming few years would increase tremendously in value.Coin like NEO,ADA,EOS,MIOTA are very strong based coins and i think investment in these coins would prove very lucrative in coming few years when their prices would reach to moon.NEO would be comparable to ETH in coming 2-3 years,ADA is another strong coins based on improvements of smart contract. etc.