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

Coinmama has become a reputable and reliable option for beginners looking to purchase bitcoin and ethereum. It has an easy to use interface, the option of instant purchasing via credit cards, and real time customer service. These reasons make it a very attractive option for people looking to get in to the world of cryptocurrencies easily.
Coinmama has a number of considerable disadvantages though. The very high fees, that can amount to 10%, on credit card purchases, are the main one. (There are no other funding options) They also don’t offer a wallet service, have no mobile application, or any additional trading tools.
Registering for an account on Coinmama is simple and straightforward. There is also a verification process, but it tends to be much shorter and less time consuming than other exchanges.
After users have opened an account and purchased bitcoin or ethereum, the funds are instantly transferred to a third-party wallet. This makes Coinmama very secure, as there is little chance of a breach.
Coinmama is able to process credit card payments because they require personal information and a government-issued ID. Furthermore, the privacy policy is very draconian; they reserve the right to obtain credit information about users before allowing them to purchase on the exchange and collect as much private information about users as they deem necessary before allowing them to purchase.
Despite this fact, it provides a basic on-ramp for users looking to buy bitcoin and ethereum for the first time.

Liquid is a blockchain platform that was created by the fintech company Quoine, that has a suite of blockchain powered financial services. Liquid is focused on providing liquidity to crypto industry. The platform offers a "worldbook" which is a multi-market order book that aggregates liquidity sources to one order book and supports trading in multiple currencies. Liquid has several features that are aimed at increasing the liquidity of crypto assets. The platform includes smart order routing, a currency conversion engine, fiat management, and other trading tools. Liquid is powered by the QASH token, which was released in an ICO that raised $105 million.