Loopring is an Ethereum-based decentralized exchange protocol with an automated execution. Loopring is not a decentralized exchange. It is an infrastructure that enables decentralized exchange. Loopring is designed to allow any platform that uses smart contracts to integrate. By pooling all orders sent to its network, Loopring provides maximum liquidity and optimal pricing across exchanges and platforms. One of Loopring's unique features is that users don't need to deposit funds with an exchange. Tokens remain in wallets and are not locked by orders. In addition to not requiring direct deposits, the protocol has innovative mechanisms built in that allow for a series of trades to be bound together in an order ring to fulfill each other. The orders can then be split through order sharing, where partial orders will be filled until the whole amount is completely filled. This unique automated execution feature increases liquidity.
Loopring wants to become a cross-blockhain protocol. It has plans to integrate with NEO and Qtum.

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

Ethfinex is a cryptocurrency exchange focused on ERC20 compatible tokens that was created by Bitfinex. It aims to be, not only a trading platform, but also a community discussion platform for ERC20 compatible tokens and ethereum-based ICOs.

Ethfinex is a hybrid decentralized exchange. Traders can choose between trustless on-chain settlement, or high speed centralized execution. By using decentralized remote portals, users can access the Ethfinex order book without actually having to deposit their funds with Ethfinex. Ethfinex also has a robust API, remote portals, and margin trading.

Ethfinex wants to be a hub for the overall ERC20 token community. It is a good option for those looking to trade tokens, but it also a platform that can be used by Ethereum developers for their crowd-sourcing needs.

Ethfinex has a user-friendly interface but it is primarily designed for intermediate and advanced traders. It offers margin trading, a crowdfunding funding market, and an active discussion forum about ERC-20 projects. It has a wide range of order types available, including the basic market, limit and stop loss orders.

Ethfinex has a variety of security features, such as cold wallets that require multiple managers to unlock. There are also a number of automatic verification tools in place, and 2-factor authentication is encouraged for all accounts.
Ethfinex features its own token, the Nectar tokens (NEC). NEC tokens are given for free to token market makers in proportion to the volume of trades they participate in on the exchange.

Trading Fees: Tiered system depending on volume ranging from 0.1%-025%