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.

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.

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