From my experience, at this moment, the two best exchanges are Binance and KuCoin because:

• Both are quite easy to use and have a fairly similar organization.
• Trading fees are among the lowest on the market.
• They also list many pairs of cryptocurrencies.
• It seems to me that they offer a fairly high level of security.

In the future, the best exchanges will have to be decentralized and they will also have to guarantee that trading transactions are carried out quickly.