Coinbase is one of the most prominent and influential crytpo companies. It is the most recognizable exchange in the United States and has over 20 million users worldwide.It is extremely user-friendly and is great for beginners. Coinbase is the intro platform for many first time crypto investors because it has a number of features such a free GDAX account for all users, a user friendly mobile App,  and built in wallet options.
There are a variety of security measures, and all funds are insured by the FDIC up to $250,000. Because of this, Coinbase is a very secure and reliable exchange with a reputable brand name
Its' clean and simple platform make it easy to quickly buy or sell cryptocurrency, and track funds through individual currency wallets.
Coinbase is a fully regulated exchange that is compliant with all laws, and because of their size and brand, they have been the subject of IRS investigations in which they were forced to disclose trading information for thousands of user accounts. They openly track user details and trading information. and have been known to close accounts for violating the terms and conditions.This is one of the main reasons that some traders prefer to use another exchange when they have become more familiar with the crypto ecosystem.
Coinbase also has  a relatively small amount of currency pairings and the platform does not have tools to accommodate more advance technical traders.
Coinbase also offers a variety of funding methods that make it an attractive choice for US residents that want to start buying crptocurrencies.Accounts can be easily funded. Since Coinbase is regulated, US bank accounts can be directly linked. This allows for relatively easy deposits and withdrawals, with a flat fee of 1.5% for buying via a US account. The trading fee is 0.25%

CEX.io is a British company that changed its focus from mining into becoming a cryptocurrency exchange. CEX has made an effort to add many coins, and boasts of fill-or-kill (FOK) orders that allow for some of the industry’s fastest trading, but it has a poor record on privacy and transparency that should give pause to traders.
The exchange’s fill-or-kill (FOK) orders are very fast, but come at a steep 7% fee. The mobile application is easy to use, and there is also an API integration. CEX is a regulated exchange that complies with all KYC and ALM laws, so they are able to accommodate several funding options, including credit cards and bank transfers.
The majority of CEX.io’s trading volume is done with bitcoin, and although they have made an effort to add more coins, this exchange simply does not have the trading options that others do. The low trading volume of other major coins provides limited liquidity for most traders.
Trading fees vary depending on trading volume between 0.16%-0.25%.Bank transfers are free and withdrawal fees are lower compared to their competitors, but transfers can take up to 20 days.
Although CEX.io is easy to use and allows for very fast crypto purchases, it has high fees, delayed withdrawal times, and a poor record on privacy/transparency.