first poloniex that I know is the exchange that has the largest trading volume and the most traders, this exchange was quite a lot of people who used it because the crypto price movements there are quite tempting, a lot of my friends who benefit there. This market has a margin trading feature that I was the best at when it appeared so that a lot of people use that feature on Poloniex. but this market began to be displaced when binance appeared and if I'm not mistaken there were bad rumors but in fact now this market has begun to be active again to promote its market