For me the best altcoin to invest is ETH and BNB. Both of them are my priorities in this year. I don't look at other altcoins at the moment.
I trust more altcoins. For instance, I started to pay more attention to TRON and Cardano - they can become good gainers in 2019 and 2010. NEO can climb up and return the popularity it had before. Litecoin will gain soon.