And while Dropbox has an ecosystem, you’d be a bit silly to not move away from that if you want cloud document editing and a web interface that actually can work on its own.
To try and help with your decision, here is a comparison between SkyDrive and Google Drive. As always, it’s completely up to you. I’ve tried to give reasons for using both services, as there are reasons.
For new users, it creates a hard decision as to which ecosystem to go into if you’re serious about going cloud. There is no definitive option. If you want an API and document editing that tries to replace desktop apps, go Drive. If you want 2GB extra, or 25GB in total if you’ve used it before, and less functional web apps, but more compatible with the desktop version of Microsoft Office, go with SkyDrive. You can still work with Office with Google Drive, but it won’t allow any web editing.
Google Docs has replaced Office for me, for over 2 years now. For what I’ve needed to do for school, I’ve never needed to use Office, bar from more graphically advanced documents. Unless you know you need something in Office, I seriously would recommend going Google as the Google Docs web editors really try to replace desktop applications, something I can’t always say about SkyDrive.
I personally have replaced Office with Google Docs for some time now and have 80GB of space, so Google Drive is what I’ll be using. But, as Terence Huynh proves time and time again, people are different and some may find SkyDrive as better for them. It’s truly up to you. Try them both out and see which one works for you. After all, they’re both available for free. I’d recommend trying to use both for an entire week, and seeing what you can and cannot do.