Gate.io is a crypto to crypto exchange based in the USA. It is an unregulated exchange and does not accept US clients. They offer one of the widest selections of tokens.

Trading Fee: 0.2%
Withdrawal Fee: 0.01 BTC, 0.03 ETH
Number of Tokens/Coins: 347

Gate.io has received many negative reviews regarding difficulties withdrawing funds.

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%

Simex is an exchange that is focused on the Russian crypto market but is registered in the United States. Simex offers a limited token selection that users can purchase with USD or Rubles. They offer convenient debit card withdrawal options.

Trading Fee: 0.2%
Deposit Fee: Up to 3.3%
Withdrawal Fee: Up to 6%
Number of Tokens/Coins: 6

Simex issued the SMX token, which gives holders discounts on trading.