Poloniex is an established crypto to crypto exchange that is based in the United States. It offers a large selection of tokens to trade and has high liquidity. Poloniex was hacked in 2014, and lost more than 12% of their bitcoin supply. They have improved their security protocols since then. In February, 2018 Poloniex was acquired by Circle, one of the largest crypto payment providers.

Trading Fee: 0%-0.1% Maker and 0%-0.2% Taker
Deposit Fee: Varying Depending on blockchain fees
Withdrawal Fee: Varying Depending on blockchain fees
Number of Tokens/Coins: 97

OKEx is a relatively new exchange that allows cryptocurrency investors to trade a wide variety of fiat and crytpo pairs. Although it is based in China, and caters to the Chinese market, it has a platform that is easy to use in all languages, and has quickly become one of the largest exchanges, by volume, in the world. The highly secure platform provides high liquidity, and has a number of other advantages.
OKEx has a user friendly interface that can be understood by all traders, regardless of their experience. Their platform is a good option for new crypto users because it supports trading of one of the widest varieties of different cryptocurrencies. It is also a good option for professional investors and day traders. They offer high trading limits, future contracts, and a number of other trading tools, including a block explorer.
Withdrawal Fee: 0.1% with a minimum of $15
Trading Fee: 0.2%

Cobinhood is a cryptocurrency exchange with no trading fees. Users can trade most of the major pairs, and a variety of other currencies. Cobinhood offers both both a centralized and a decentralized trading platform. In addition to their cryptocurrency exchange, Cobinhood also operates an ICO underwriting service, and they are releasing Zeux, which will be a crypto mobile payment and investment app.
The network is powered by the COB token.