I can't say much about FTX because I am not a user of this exchange.
However, I am a regular user of binance and kucoin, and so far, I haven't encountered any issues.
And also, in any exchange, you should not store your funds too long for security purposes.
So I think, whichever the user uses here for trading, these 3 are quite trustworthy.
And by the way, if you are a small trader, kucoin has still no kyc with 1 BTC daily withdrawal limit (but they are not licensed to operate in US).
Kucoin doesn't allow USA people? Some users comments that FTX also don't allow USA people so the last choice would be binance. There is also binance USA, this could be another version of binance specifically built for USA citizens.
I must point out here that FTX offers withdrawal free of charge. many times I wanted to withdraw BTC from Binance (earned by trading) but I didn't want to pay them 0.0005 fees. then I mostly convert it and in the end, I have something completely different in my portfolio.
though I am quite accustomed to Binance, I am slowly getting used to FTX.