Well if you wanna sell a token you have to see where's it listed? Is it in any cex or dex.
If you like to be secured and wanna get a taste true decentralized system in crypto, dex is best I mean wallet. If you don't wants so difficulty cex is good for you.
Overall depends on your taste . If you looking for a little bit cost cutting then Cex is also useful for you cause cex don't charges any network fees for trading.
I hope you get my point
Well when we are talking about the fees and having an option of wallet and exchange, I will prefer to choose an exchange and it is a centralized exchange that commonly has low fees. Buy and sell in your wallet is usually has high fees, just like the Coinomi app wallet, I used this before buying and selling crypto but I did not know that I have terrible fees to pay which is what I realized after having a third transaction there. The best is a centralized exchange and I am using Binance since there is an option that you can minimize your fees but for other reasons, a wallet is the best and safe to store your crypto, not on the exchange.