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%

BitFinex is a bitcoin to fiat exchange, a margin trading exchange, and a liquidity provider. The platform offers a number of features that expand the financial positions you can take - for example the ability to short Bitcoin via margin trading.
The exchange also offers a set of other cryptos apart from bitcoin such as Litecoin and Ethereum.
Deposits and withdrawals take place via the standard bank transfer means with fees of 0.1% and a minimum of $20. Bitcoin and Litecoin are free.
BitFinex takes security seriously and have moved from a hot wallet cold wallet set up to segregating customer funds where each user has access to their own wallet which they can review on the blockchain.
Bitfinex was hacked on 03 August 2016 and around 120,000 BTC were stolen.
Fee of 0.1% for most trades

Kraken is a US-based cryptocurrency exchange and one of the largest bitcoin exchanges in terms of volume and liquidity.
It provides Bitcoin pricing to the Bloomberg Terminal and has considerable influence on the overall crypto market. Kraken offers a number fiat funding and transfer options.
There are 18 BTC pairs and 16 USD pair to trade
Fees vary depending on the volume - for main trading pairs this is between 0.1-0.35% - however for other less common crypto pairs the range can be as low as 0.05% or as high as 0.75%. There are also 0% fees for some trades.
Withdrawals and deposits are variable depending on the method - although in general all fees are 0.19% with a $20 minimum.