Bittrex is one of the largest crypto to crypto exchanges. It offers a large number of trading pairs, but do not allow fiat to crypto trading. Bittrex has one of the largest trading volumes in the market.
It is a reputable exchange with good record on security and is also fully regulated. They provide two factor authentication as well as a number of other options to secure funds. They are United States based and are fully compliant with all laws.
They support more than 190 cryptocurrencies and have a dynamic platform. It’s a good option for both advanced and beginner traders; providing advanced tools like candlestick charts and crosshairs, but with a user-friendly interface that is very intuitive.
Trading Fees: 0.25%

Covesting is a cryptocurrency exchange that allows users to copy crypto trading behavior of other traders. The platform offers a range of currency pairs and has a native COV token, that gives holders a 50% discount on trading fees, and is also used as a bonus system for traders whose activity is copied.
Trading Fees: 0.15%-0.25%

DigiFinex is a top 20 exchange that has a strong focus on China. They do not accept US clients. DigiFinex's exchange does not charge a withdrawal fee.

Trading Fee: 0.2%
Deposit Fee: 0
Withdrawal Fee: 0
Number of Tokens/Coins: 29

DigiFinex issued the DFT token, which gives holders dividends.