Idex and etherdelta are the most common decentralized exchange I use especially when I want to buy erc20 tokens or when I want to sell it. For regular trading, I still use the centralized one since I mostly trade in btc/fiat pair. Decentralized exchange is good at one side but centralized exchange still better at some points.
I use IDEX over Etherdelta because it's more popular now and has a cleaner interface compared to Etherdelta but I think there will be a big decentralized exchange that is soon to come, which is the Binance Dex.
Relevant news about this one has a latest publication today.
New Binance DEX Testnet Launches in Less Than 24 Hours: Here’s What Users Need to Know