I think altcoin is other than Eth, which has the potential of EOS, MONERO, NEO, BCH, or LTC. This coin has a good future and gives coins a chance to grow with your luck.
there are many coins that have good potential for the future, but that depends on crypto conditions. if crypto is increasingly developed and accepted by many people, there will be many altcoins that will be increasingly valuable. therefore it would be safer to hold a coin that is already strong in the market because we don't know what will happen tomorrow. and I think ETH is still the best.