This cryptocurrency exchange is the largest one out there, period.
Coinbase was launched back in 2012, and it can be used in more than 32 countries – supporting bitcoin as well as several altcoins. This exchange also offers offline storage and a mobile wallet, in addition to insurance protection for if your coins are stored on their servers.
Pros: Easy to use, several payment methods, online wallet
Cons: A bit of extra work needed to verify your account