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

B2BX is a cryptocurrency exchange and B2B crypto-trading service provider. In addition to its exchange, the company offers financial companies the tools and services they need to set up and manage their operations. The B2BX exchange offers B2B token holders a 35% discount on trading fees.

United Traders is a Russian-based software company that is developing an investment marketplace and crytpocurrency exchange. Their Aurora platform allows traders to access some of the largest traditional asset exchanges. The UTExchange will offer smart-route technology to address liquidity problems that face cryptocurrencies with smaller trading volumes.