While Dropbox was the original online storage unit, Google Drive has quickly caught up offering more space with its free accounts, access to file creation tools that Dropbox just doesn't have and more upgrade options for additional storage. Dropbox does have block syncing which makes saving file changes faster and more reliable than Google. However, overall, Google Drive is still the better pick.
I personally use MEGA but I've been using Google Drive for storing documentation for projects in the past. I will have to give the pass to Google Drive, especially because you can easily edit Word, Excel etc files without having to download them first.