as long as the altcoin you choose is altcoin which is in the top marketcap position, I don't need to worry anymore, but I also suggest that you also choose ethereum as one of your investments.
Choosing Ether now, you need to wait at least for spring 2020. It will be natural to suppose that ETH will grow close to its revolutionary Ethereum 2.0 start. There are other altcoins, which are worth our attention, and you can work with them now, holding the cryptocurrency #2. First of all, pay attention to Zcash - it resembles Bitcoin and it has a great privacy and anonymity.