Viewer Jack sent this one in: Yet Another Cloud Storage product for you to look at.
I like it because it support secure FTP, SSH, etc.
Your own Dropbox Clone will always be a good option if you want flexibility, customization, control, and savings, not to mention a little more security. A nice thing about GoodSync is it offers SFTP secure FTP file transfers, and can sync to online storage medias.
Download is a breeze. It's only available for Mac, Windows, Android, and iOS (NO LINUX) though. Then you can create your first job (do two way syncing, or one way backup). I'm setting up a two-way sync for my example. I'm syncing a special desktop folder to my Dropbox and vice-versa. If you want to make this into a clone of Dropbox, you can set up a web host who offers space for file backup and SFTP your file transfers via GoodSync.
Once ready, you want to choose your 'right' and 'left' folder syncs. My left one is my GoodSync folder, my right one is Dropbox. If you want to connect your own dropbox account it'll ask for authorization via Dropbox's site (also a good time to turn on two-factor authentication on your Dropbox). Hit analyze. Depending on the size of your data, this will take a while to analyze all of your available Dropbox folders and files so you can customize which ones you want to sync, etc. Once customized, you can Sync. There are a few other additional options as well. If you click Auto before you sync, you can customize when your sync happens, and in what way. You can set File Versioning under the General settings or change the sync from two-way to one-way. Filters will let you exclude certain files, and Scripts will allow you to change name, date, time, format, etc.
Pros: Lots of customization, fast, and allows SFTP, as well as syncing to online storage. You can also get versions for USB to automatically sync to your USB drive. Cons: May be too much customization for some people, and you have to pay to get things like Syncing to Google Docs, and... it's not open-source.