Without more info from you, i can't just tell you that dex has more reputation and security because there are many dex that use smart contracts and are a product of DeFi, and many of them aren't truly decentralized nor exactly safe, but since you posted this in the BTC discussion board, i believe you are looking for p2p exchanges for trading BTC.

You have options for truly decentralized p2p exchanges like Bisq, AgoraDesk, RoboSats and others, in terms of security, they are more secure because there isn't really a single point of failure and customers control their funds and trade p2p, but most people use cex because it has more liquidity, even though it is less secure and private than a true p2p exchange like Bisq for example.