In recent years, a lot of crypto-currency exchanges have appeared but this process can not continue indefinitely. Most major players are still guided by the TOP exchange - Binance, Kucoin....., etc. Perhaps in the future the list of TOP will change.
I guess Binance is the most popular exchange that is used for trading for now. Though there is an issue about on the security and become victim by hackers. I also used HITBTC but the issue is long time of transferring the coins.