Dropbox is a great tool if you love to have all your important files in sync across all the devices you own. On the other hand, Google Docs is a great service to manage your documents over the cloud. The functionality that Google Docs misses is that you can’t have offline access to the files. (NOTE: If you have turned on the Google Docs offline mode you can access Google Docs and edit the documents, albeit you won’t have the access to files). Insync is a much simpler solution which works similar to Dropbox syncing model.