Honestly i never try kucoin but i heard many good feedbacks about it therfor i would still prefer to use binance as i have an account on it and i also like their service to the fact that thier fees are quit low when compared to some other online exchange , their costumer support also reponds verry quickly based on my past experience on them. Kucoin exchange on the other hand is only good because they trade other unkown coins that you cant find in other exchanges like binance but overall both exchange are verry legit and authentic.