Bitstamp is one of the most popular fiat to Bitcoin exchanges. It was one of the first big exchanges and it provides customers with a platform that is secure and easy to use. It was originally started in Slovenia but has moved its' operations to Luxembourg.
Bitstamp uses MultiSignature technology for its hot-wallet, as well as a fully insured cold-storage option where kept off-line. They also offer a number of other security features such as two-factor authentication and confirmation emails to enhance account security.
Bitstamp provides the option for limit orders, stop loss, and trailing stop orders. They have an easy to use API that can be integrated into user applications. T
Overall, Bitstamp is a secure and reliable exchange with good liquidity and a solid infrastructure. It is a good option for beginning traders as well as more advanced crypto holders.
Trading Fees: Tiered system depending on volume ranging from 0.1%-025%

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.

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%