There are many crypto-currency exchanges which are great and promising position in the market. In my opinion, the 7 best exchanges are -

1- Binance : This is the best and number one in 2019.

2- Kucoin : I use many coins and this is my favourite .

3- Bittrex : Bittrex has the best customer supporter.    

4- Hitbtc : It is a high quality exchang.
  
5- coinexchange : I use coinexchange and love it to exchanges.

6- BitMax : This is a fast growing exchange.

7- Coinbase pro : Trading on Coinbase Pro is very promising and aggressive, from beginnin,  i use coinbase and it’s performing so well than more i think.