In my opinion the best promising altcoins for 2019 are Cardano, Ripple, stellar, Pundi x,Litecoin and Neo.
BAT, EOS, and Raven coin attract much attention. EOS i is technologically better than ETH and BTC, and it can grow better. Raven was not known for a long time, but recently it showed activity. Their main idea was to create a convenient and secure cryptocurrency network in which you can quickly exchange any assets: gold, fiat, securities, shares, etc. BAT also has a good future.