I've been using the DEX exchange since 2016, then in 2018 there were several New Dex including ForkDelta. Idex and Bancor became Dex who have the option of buying crypto using Visa, but some Dex have implemented a KYC system, then I switched to Uniswap exchange and still use Dex exchange.
Cex is actually good, but there are third parties, just like the bank and all control of the wallet does not belong to the user, because at Cex, we don't have the private key of the wallet that we own.