Is bitcoin an exception? if it is, I think that the fastest growing coin is BNB. Started almost the same date with Bitcoin Cash but compare to that coin BNB has been performing well for the fast two years. Since its launched, the price soared and even managed to survive during the bear market.
Chainlink too I guess. I can't think of any other coin that has performed well.
If you going to see the ranking of cryptocurrencies in the coinmarketcap the BNB enter in the top 10 so basically, binance coin is totally one of the fastest-growing coin in this year 2019 and when I see this coin the price is around 3$+ but now it's around 15$ and I know it already hit the price of 30$. I think there are many fastest-growing in this year but for me, the number 1 is the binance coin.