But at several that have good reputation, I think It's also safe.
it's my opinion
Did you mean that exchanges are also safe?
I don't know how they are safe. They do not provide your private key, which means you do not have control over your Bitcoin. You do not have a coin control feature, which you could utilize if you send Bitcoin accidentally to the wrong wallet address. If your email gets hacked, the hacker could access your exchange account as well. So, how do you consider a exchange as a safe option?
Exchanges has many negatives sides. For example, they have some limits when you send your Bitcoin to another address. Usually exchanges charges too much high fees on withdrawals. For example, Binance's minimum withdrawal is 160K satoshi and the withdrawal fee is 70K satoshi. Can you imagine?