Ease of Use

Drag n' Drop to one folder. When it comes to simplicity, Dropbox wins hands down. You have a Dropbox folder, drag files into it, and magically the files appear in identically named folders on your other computers.

Sharing files for collaboration on Dropbox is also just as easy: from the website, go to the sharing tab, select the folder/files and enter the email addresses of people you want to share the files or folders with.

Like Dropbox, but with multiple folders support. SugarSync has similar functionality, with its Magic Briefcase folder, but because you can sync multiple folders on more than one computer, managing your synced folders and shares can get more confusing.

Easy visual clues. Both Dropbox and SugarSync have handy tray icons and integrate well with Mac and Windows. There's a visual clue over folders to show whether they've been uploaded or not, and you'll be notified if you get near or go over your file storage limit.

Traditional file management interfaces. SpiderOak and Wuala have folder management user interfaces that aren't really difficult to understand or navigate, but they do require just a bit more thought and planning than simply dumping everything in a catchall folder. Live Mesh asks you to select each folder you wish to sync individually. By allowing you to select which folders to backup/sync, however, you get more control (a good tradeoff between simplicity and power.

We've previously posted a workaround using a symlink and a small Windows app for syncing files and folders outside of the dropbox folder, if you prefer more control over Dropbox's simple "one folder" access).

Backup separate from syncing.

Of the five services, SpiderOak's interface/system may be the most awkward and confusing to set up. With the other services, you select the folders you want to backup/sync and the app starts to make that happen. With SpiderOak, you first have to choose your folders/files to back up and wait for those files to be uploaded. Then, in another screen, you have to choose the folders you wish to sync between devices.

This might be good in corner cases where you want to backup files to the cloud but not sync them to another computer, and it also eliminates some overhead by separating the backup and sync function. From a user standpoint, however, it may feel like an unnecessary step. Wuala also separates the backup and syncing function (though you don't have to first backup in order to sync), so clearly these two services are designed for people who may want more options than just syncing.

Security & Privacy Policies

SpiderOak and Wuala both shine in the security department, because, unlike Dropbox, your data encryption key is only saved on your computer. SpiderOak has a well-publicized "no password storage" policy stating your data and even filenames are inaccessible to the company.

Dropbox's reputation, on the other hand, has dramatically dropped recently due to recent security mishaps, awkward terms of service changes, and the fact that employees can, after all, access your unencrypted data.

While we don't think there's a major security concern here we do recommend you encrypt any sensitive data stored within Dropbox (or any online storage service, for that matter).

The other service providers haven't come into as close scrutiny as Dropbox. Here's what these service have to say about their security practices:

• SpiderOak: "SpiderOak never stores or knows a user's password or the plaintext encryption keys which means not even SpiderOak employees can access the data. Our zero-knowledge privacy approach means we can never betray the trust of our users" SpiderOak also recently added 2-factor authentication.
• SugarSync: "We use industry best practices to ensure that your data is safe and secure. Your files are transferred securely using TLS (Transport Layer Security) and are stored in the cloud in an encrypted format using 128-bit AES-the same level of protection used for online financial transactions."
  
  
• Live Mesh: This clear-Cloud post says that files stored on Microsoft servers are protected by access controls but are not encrypted.
• Wuala: "All files are directly encrypted on your desktop.
  
  Your password never leaves your computer. Not even we as the provider can access your files or your password. Wuala employs proven encryption technology (AES, RSA and SHA) to secure your data."

In short, SpiderOak and Wuala definitely have the most assuring security policies/practices, but you still want to take matters into your own hands and encrypt any and all sensitive data stored online.

Performance

Both Dropbox and Live Mesh performed best in my tests because they both synced directly over my local network, without having to go through the online servers first, as these syncing services typically do. Dropbox's LAN sync and Live Mesh's local sync are unique and very useful time-saving features if you use these services to keep computers on your home network in sync.

You can also use them, of course, for syncing computers and devices that aren't on the same network.

Otherwise, the services all performed relatively the same, with barely any noticeable difference when saving new files or deleting them. I found SpiderOak just a bit faster but more resource-intensive in the initial folder upload than Wuala, while SugarSync took up more system resources than the others in the background.

Sharing

All of the services make sharing files with others very easy. Just right-click or select the files/folders and enter the email addresses of your recipients.

With Wuala and SpiderOak, you create groups or "share rooms" (SpiderOak's comes with its own RSS feed) to distribute to more people at a time, so it feels more of a collaborative environment.

In addition to this folder sharing for collaboration or to give others access to your files, all of the services also let you create public links to your files so you can post a link on Facebook to a document, for example. SugarSync has direct posting to Facebook Photos.

One major downside to Dropbox is that files shared with you by others count towards your allotted Dropbox space, and, like most of the services, you also don't have any control over the permissions of the folder.

For sharing and syncing a read-only folder, SugarSync may be your best bet because you can specify folders to be read-only and password protected. Depending on your settings, you may also be able to control editing of files in shared files for groups with Wuala.

Conclusion

As we've mentioned before, you can use multiple online cloud storage services to make the most of the available free space. For your work documents, for example, you might select SpiderOak or Wuala; for streaming music on your mobile phone, SugarSync; to backup files from one computer to another over your local network, Live Mesh; and for everyday files, Dropbox.

If that's too much overhead, however, the decision for which online syncing service is right for you will depend on your priorities: simplicity and third-party support (Dropbox), security (SpiderOak/Wuala), Windows advantages(Live Mesh), or most features and platforms support (SugarSync).

Now that you've seen our thoughts, what's your take on these or other online syncing services......................