We use Box.com (as opposed to DropBox) and love it. Super easy to use and it has been adopted by all business functions across our company - and that was by popular demand, not pushed by IT (or finance).
Yesterday Google announced the "Google Drive" so that's yet another option and undoubtedly attractive if your company uses other Google apps already. Gizmodo did a cursory overview of the major cloud storage systems which could be a useful item: http://gizmodo.com/5904739/google-drive-icloud-dropbox-and-more-compared-whats-the-best-cloud-option.
The feature sets are getting very similar (although DropBox may be the only one with "team sharing"). But, if you're looking at personal use or a very small business or department situation its hard to beat Microsoft's free 25gig starting point.
Also, they all start as free products so its dead easy to try them all or even to use them all long term. I think we're all used to having certain files on certain network drives; so it shouldn't be difficult to split your cloud storage and have different types of files on SkyDrive, DropBox, and GDrive.
They are both equally good. With DropBox, the max storage is 18GB in a free account. With SkyDrive, the max storage is 7GB for a free personal account. They offered 25GB but that was for sign-ups prior to Apr 22
What makes all of these options possibly unique is what rights you give them to data mine your storage.
Did you really read the Terms & Conditions?
Neither. I always feel there should be a concern for company data compliance and security when utilizing these free cloud storage applications. Does a company really want to share proprietary information with MSFT, Dropbox, and/or Google? Once you upload your file, you have basically giving that organization rights to your file. The majority of these services are not HIPAA compliant; much less do they offer traceability of the shared file. The free online storage has it place with personal non-relevant data storage. I would never upload a company file, it could come back to haunt you. I would suggest a server drive via VPN or secure FTP, which there are several methods.