So, what I think makes an exchange top-tier, firstly strong security measures that protects user funds, and having top notch customer support secondly earning opportunities like Launchpool, PoolX, savings, staking and more, and thirdly, user friendly interface that makes your trading more easier and having powerful trading tools like copy trading, futures and etc. That's my opinion of what I think is to be a good exchange. You guys are free to add or correct me if there are any..
No exchange can protect your funds, you're the only one that can give yourself a guarantee protection by making use of a self custody wallet (preferable, a hardware wallet) to avoid hacks.
Exchange can't protect you irrespective of all the lies they feed you to give them control of your coins that they then leverage on to make money for themselves. Exchanges aren't different from the banks and neither of them should be trusted. For the fact that you have to hand over the custody of your coins for you to earn an opportunity through staking should be a red flag for you and it should be avoided.
Things that should have made an exchange top tiers are being ignored because CEX are deceiving we all and taking over the exchange space. Things like how decentralized are the exchange and other top Dex features should be what we should use in rating exchange and not who can give us fake hopes with earning opportunity and safety that isn't guaranteed.