A Favorites Section
Though the Files app on iOS could use a lot of work, one thing I really like is that I can save a files and folders under a favorites section. That would be great if OneDrive offered something like that. That way I can quickly get to the folders and files I use the most. The Files app does not handle document previews, outside of PDFs, very well and I like how OneDrive does this. Plus I love that I can just click on the Word, Excel, or PowerPoint icon and it will open it in that app, instead of making a copy.