As the name suggests, this one is for Apple users, who get this as a default with their device. For those who have an Apple account but rely on other services for mail, iCloud can work as a good backup with all files created on the iPhone or iPad being synced to this account. It is simple to use and has no clutter. As you would expect from Apple, there is no advertisement sharing space with your mail. The web client also gives you access to other Apple services like Calendar, Contact and Notes from the same landing page.