I use Box for work, their desktop sync software works pretty well. All of my work documents are on there and its seamlessly synced between 5 devices. I like Box because setting permissions and sharing with colleagues is easy and it allows assigning tasks, comments, and tracking revisions etc (the things I need for work). Also, Box has a lot of plugins and stuff for your browser and programs that aren't available yet for Skydrive. Skydrive integration with Office 13 is great... but I would have to mix work and personal documents on Skydrive.
The only reason I don't use Skydrive for both work and personal is that WP8 doesn't support two live profiles (and its a pain in Win8 to use 2 profiles) and I don't want to mix work and personal. If MS ever allows dual profiles (which I think they will eventually, lots of positive press for BB10 for this) I'll probably use Skydrive how I use Box.
IMO both are great, but each is better at different things.