my favorite dex is to stay on old dex like forkdelta, etherdelta and the latest one i am still feeling comfortable using binance. The reason is that first I feel comfortable with the three dex, and why more than one dex, it is to make it easier to compare prices, sometimes prices differ due to local time, so I choose which dex is more appropriate, the price is suitable and actual, of course.
I prefer to use Idex because this is a decentralized exchange that is easy to use and very famous in the last 2 years. Currently, exchanges like Etherdel and Forkdelta are all very low liquidity, so these two decentralized exchanges will not be interested by many people in the near future. Of course Binance Dex is also a very potential option but this exchange is still very new and still has a lot of restrictions when trading.