in my opinion a good and good exchange presents a lot of factors including the volume of sales, the number of coins listed and the low fees that can be a good exchange and attract many investors or traders to be there.
The trading volume can be manipulated, it cannot be a factor that makes an exchanger a good exchanger. so I continue to argue that security and service for 24 hours a day is the most important thing in an exchanger to be said to be good.
That could be true, I read an article about that and I like to share it here, you can refer to the link below.
https://www.theblockcrypto.com/2019/05/28/up-to-86-of-total-reported-cryptocurrency-trading-volume-is-likely-fake-according-to-analysis-of-exchange-website-visits/That would mean only few exchanges in the market are reputable, and we should trust them over the questionable exchanges.