Both KuCoin and Binance are good exchanges, I think Binance has been so popular because it has been able to bring a large number of coins to it's exchange and people like having choices. KuCoin has a very clean feel and one of the best of all crypto websites I have visited.
The interfaces of both exchanges are very similar and have provided me with fast trades without any real issues.
I would rather use the KuCoin site but because of the limited number of good names I had to add Binance. I would really like to see STEEM on one of these sites. I guess I will have to open another exchange account where STEEM is sold.
In the end it's really not about which one is better but which one has your favorite coins. Keep in mind that there is always the possibility that one of these sites gets hacked but there is always that possibly with any exchange.
KuCoin Favorites:
KCS - NEO - GAS - EOS - WTC - AION
Binance Favorites:
BNB - IOTA - ICX - ADA - NEO - GAS - EOS - WTC - AION
