give Nash a try they also will add Btc and bch by the end of the year
https://nash.io/Isn't this a centralized exchange? OP's asking of the best decentralized exchange and here you are suggesting this one.
To OP. It depends on your preference.
If you want a fully decentralized exchange with the freedom to just list random scam/shit tokens and have a nostalgic Etherdelta vibe, then go with Forkdelta.
If you want a decentralized exchange that would require you to go through KYC process and also lists various shit tokens, go with IDEX.
If you're lazy and don't want to fill in any order books, go with Bancor. (Some say this isn't a dex at all, but who cares.)
See? Easy choices. LMAO.
DEX's typically has low volume not to mention low to no support. So, if you really want that. Then sure, you can try the three I've mentioned.