Kucoin is by far one of the safest and securest exchanges that haven't been hacked. It's time-tested and words very well. It has many altcoins added, so KCS can become big in the next bull, which is already started. Kucoin is a reliable choice. Well, Binance was hacked, though they replenish all lost funds, so no big deal for users.
You can say that until the day that exchange is hacked. I believe all exchange are susceptible to hacking, meaning there is no safe exchange platform in the internet space. We better keep our stuff in our own stash and use only exchanges if we want to trade. I am a user of Kucoin myself but I never use it as bank to store my tokens and coins.