I have used a lot of exchanges like Binance KUcoin BYbit Pancakerswap but the worst one is p2pb2b. this is a very worst exchange for me because when I use it, I always got lost because of its chart.
Never even heard of that exchange and at first sight, I thought you are paying p2p trades haha
For me the worst one has to be yoshit because they are shit and list any coin plus the exchange is a well known scam and while I didn't got scammed, I never had an easy time trading there.
I think the best one has to be Binance given how picky and careful they are when adding new coins and while their support sucks, there aren't many problems I have had on this platform for over a year or two now.