KuCoin and Binance are too great exchange site with a high volume everyday but I must prefer to use Binance since Im comfortable with the design and ui of this exchange site it has also an android application that easy to use the withdrawal transaction are good over all Im satisfy to this exchange site.
I always prefer Binance because it has a huge trading volume compared to KuCoin. Though, KuCoin is also a great exchange, it has a nice looking user interface but their trading volume is kind of low compared Binance. I see the KuCoin is following the footsteps of Binance, I wish them all the best in the world.