IMO WavesDEX is the fastest (almost fast as a centralized exchange) and easiest available DEX nowadays.
Gateway allow you to trade with BTC, ETH, ect... and fiat.
Even if you don't endorse Waves, you are not forced to trade with Waves pairs.
https://dex.wavesplatform.com/What are the fees for waves dex exchange?
And is KYC procedure mandatory for normal use or only when using FIAT?
I have it installed, but I did not used it recently at all.