This is a comparison of the Terms Of Service between Google, Microsoft, and Dropbox
"By using our Services you provide us with information, files, and folders that you submit to Dropbox (together, "your stuff"). You retain full ownership to your stuff. We don’t claim any ownership to any of it. These Terms do not grant us any rights to your stuff or intellectual property except for the limited rights that are needed to run the Services, as explained below."
"Except for material that we license to you, we don’t claim ownership of the content you provide on the service. Your content remains your content. We also don’t control, verify, or endorse the content that you and others make available on the service."
"When you upload or otherwise submit content to our Services, you give Google (and those we work with) a worldwide license to use, host, store, reproduce, modify, create derivative works (such as those resulting from translations, adaptations or other changes we make so that your content works better with our Services), communicate, publish, publicly perform, publicly display and distribute such content."