Ethereum is the best altcoin after Bitcoin, and its technology is also the most stable. In addition to the Ethereum, I like the coins ACT, ITC, EOS, OKB, these are my investment, and I am the most optimistic.
In addition to that I would prefer GAS, ADA and some ICO coins to get the portfolio little aggressive as if the coin is worth it than I can buy at discounted rate during the PRE ICO stage and during the listing can make a huge gains and give me profits.