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.

Bittrex is one of the largest crypto to crypto exchanges. It offers a large number of trading pairs, but do not allow fiat to crypto trading. Bittrex has one of the largest trading volumes in the market.
It is a reputable exchange with good record on security and is also fully regulated. They provide two factor authentication as well as a number of other options to secure funds. They are United States based and are fully compliant with all laws.
They support more than 190 cryptocurrencies and have a dynamic platform. It’s a good option for both advanced and beginner traders; providing advanced tools like candlestick charts and crosshairs, but with a user-friendly interface that is very intuitive.
Trading Fees: 0.25%

Poloniex is an established crypto to crypto exchange that is based in the United States. It offers a large selection of tokens to trade and has high liquidity. Poloniex was hacked in 2014, and lost more than 12% of their bitcoin supply. They have improved their security protocols since then. In February, 2018 Poloniex was acquired by Circle, one of the largest crypto payment providers.

Trading Fee: 0%-0.1% Maker and 0%-0.2% Taker
Deposit Fee: Varying Depending on blockchain fees
Withdrawal Fee: Varying Depending on blockchain fees
Number of Tokens/Coins: 97