Which cloud storage service is best: Google Drive, Dropbox, or SkyDrive?
Google Drive requires, unsurprisingly enough, a Google account. In typical Google fashion, access to the service is getting rolled out slowly: You'll see a note about whether Google Drive is enabled for your account or not on the Google Drive webpage, and you can't download or install the software until your account becomes eligible.
Like Dropbox and SkyDrive, installing Google Drive on your computer creates a special Google Drive folder; files you drop in there sync automatically to the cloud. Google Drive also uses tiny indicators atop your icons to indicate whether files are still syncing or fully backed up onto Google's servers—and those indicators appear on both Windows and the Mac, unlike SkyDrive's.
You get five gigabytes of storage with Google Drive. That's more than Dropbox, less than SkyDrive. You can upgrade to 25GB of storage for $2.49 per month, 100GB for $4.99 per month, with tiered pricing up through 16TB—that's 16,384 gigabytes—for $800 per month. SkyDrive's pricing is slightly better for the normal-sized options; Google Drive is the only option for folks needing 16TB of cloud storage.
Like SkyDrive, Google Drive lacks Dropbox's contextual menu options on your desktop for getting quick links to share your files. Google Drive's Web interface—which bears a significant resemblance to Google Docs—does offer various sharing options, including the ability to make a file public, share it with specific people, or share it with specific people along with giving them the ability to edit your files. As with both SkyDrive and Dropbox, you can drag files directly onto Google Drive within your browser of choice to upload them that way.
There's a Google Drive Android app, but an iOS app is listed only as "coming soon", and there's no word on Windows Phone 7. Google told All Things D that the iOS app "is 98 percent done, and it will be here soon."
Like Dropbox, Google Drive allows you to choose files and folders to sync selectively. If one of your computers needs access to Presentations, but another doesn't, you can deselect that folder on the second computer, without removing Presentations from your Google Drive completely.
Google Drive also syncs hard copies of your Google Docs documents to your desktop—sort of. You'll see files, which you can in turn double-click, but doing so simply launches your default Web browser pointed to the proper URLs.
The Android app is straightforward to use, offering options similar to the comparable apps from its competitors. One clever option unique to the Google Drive app is the ability to create a new word processing document or spreadsheet within the app.
There's been some talk on the Web about the services and their different terms of service and privacy policies.
All three services make it clear that you maintain ownership of your data that you store with them. You'll need to decide for yourself whether you trust Microsoft, Google, or Dropbox with your data.
Which to choose
If you're wondering which cloud-storage service is right for you, consider that you may in fact be asking the wrong question: These services are all free, with charges only for extra storage space. You needn't choose just one; you can install all three services on your computer, download the apps, and use them for different purposes.
Files you expect to need to share frequently may be best suited to Dropbox for the time being, since it allows you to easily share documents from your desktop. It may also be the best choice if you want to access the data from within mobile apps, since more apps support Dropbox integration. If you want to access your files on an iOS device, don't store them on your Google Drive until an iOS client is released. SkyDrive seems to be better-integrated with Windows than with the Mac, for now.
Each service is easy to set up and configure, each has some advantages, and they work fine in tandem. Try them all, and let us know which one you prefer in the comments.