Bitmex is not good... Once i was in profit and wanted to sell but for 3-4 hours it continously shows platform busy and then the price came down back to loss. So i would not suggest bitmex.

Binace is the best exchange it gave me 1Binance coin free when I traded on their exchange and that is worth of 15$ and i was happy with binance platform.

Kucoin is good because if you bought thier coin KCS then you will get every coin as a daily as a bonus from what they charge to its users.