Amazon's unlimited plan costs $59.99 per year for all file types. A separate photo-only plan costs just $11.99 per year, and includes an additional 5 GB for other files. Both plans come with a three-month free trial. (Amazon Prime subscribers already get unlimited photo storage at no extra cost.)
The only other company offering unlimited storage is Microsoft, through its Office 365 service. Microsoft's Office 365 Personal plan includes unlimited OneDrive storage and one installation of Office for $70 per year. An Office 365 Home plan includes unlimited storage for five users, plus five Office installs, for $100 per year.
Among limited storage plans, MediaFire's rates are the cheapest, charging $30 for one year with 1 TB of storage (though the annual rate doubles to $60 after the first year). Dropbox's 1 TB plan costs $99 per year, and Google's 1 TB plan costs $9.99 per month with no discount on annual subscriptions.
If you go the Amazon route, keep in mind that Cloud Drive doesn't have proper desktop sync software like most other storage services do. That means you must manually select any folders or files you want to upload, and manually download files back to your PC when you add them to Cloud Drive from another device. Amazon does at least have automatic photo backup apps for iOS and Android.
Why this matters: Amazon's new storage plans further demonstrate that low cost-per-gigabyte is now table stakes. The main distinguishing factors will be the additional services on top, whether it's a free Office installation from Microsoft, superior third-party app support from Dropbox, or the vast array of Google services like Gmail and Drive that benefit from additional storage. Amazon hasn't quite figured this part out, but it's at least taking a seat at the table.