For me it's definitely ADA and TRX. The guys do a lot this year. Maybe in 2020 we'll see them in top.
Keeping the rise in the market value of the top coins, I see Bitcoin the leading of them all and this is the best coin not just for 2019 but for the past ten years and with a growth rate like this, it might go on expanding. ETH and BinanceCoin are also good options for investment. It is my list of good coin. You might disagree on the basis of your knowledge and experience.