In your opinion, what is the best UI/UX for exchange you ever seen?
In terms of searching a good or top exchange coimarketcap is the best on this things.
But in choosing the best options platform exchange I recommend Binance, Kucoin, Coinbene,
Houbi, and Okex. then on decentralized platform Idex, Waves, coinexchange and Mercatox.
Read carefully what OP ask in this topic. He doesn't ask what is the top exchange, they ask to hear from other users his experiences with exchanges, and which one is most friendly to use them. Coinmarketcap is not a reliable source, it is known that they increase trading volume for some exchanges.
Kucoin, in my opinion, have the best UI/UX.