So basically you want and high reputable exchange that never be a victim of hackings or not possible to get hacked so it will be totally safe for everyone to store their funds? That kind of exchange won't be exist, hackers will be always smarter time by time. Also, everyone are supposed to not storing their assets on any exchanges. You can trade and make profit there but store your assets only on your private wallet.
We don't need to have that kind of exchange as we are supposed to trust no one.
It is true anything on the internet could be hacked so that is why we need to be the one to keep our funds safe,
We have plenty of exchange that are trusted and have a good reputation the one that you are looking for is so impossible because no matter how great their security is,
There would always be a way for a hacker to hack their system.