Allow documents to be fully previewed.
Google Drive excels at full document previews. I use online storage as a personal search engine for my documents. In GD, I can view/preview them online without loading another website. I am not interested in editing for my use case -- just search and find. GD's search inside preview also excels because it highlights all the matches. This is AMAZING for searching PDF documents. As long as I have to be shuttled to Office Online to see my documents, GD is my choice for document search.