In my opinion best results will show EOS and XEM. Xem is fundamentally good coin with working team, while Eos is hyped enough to give profit to holders in 2019.
Middle echelon consists of Ether, Ripple and Stellar. Maybe in 2019 Stellar will show something that will make it more interesting for investors than XRP.
Other coins - I don't know if they will show great results in next year. Who knows, maybe we will see another one on their places.