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%

UNUS SED LEO is an initiative started by Bitfinex that is focused on increasing the exchange's transparency. UNUS SED LEO means "one, but it's a lion" in Latin. The iniatative was created to increase the transparency of the exchange's finances, following a controversy related to the allocation of reserves from the stablecoin Tether, that was created by the same parent company as the Bitfinex exchange, iFinex. It is built around a token burning redemption mechanism which is tied to the parent company's revenues. Their dashboard provides insights into the fees that are collected, and the LEO tokens that are burned.

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.