1,088 votesStevenF commented
I haven't seen anyone mention this yet, but there is a nice app for Android called Autosync that works great. There are versions for OneDrive, Google Drive, Dropbox, even one for MEGA. Autosync for OneDrive lets you select which folders or files to automatically sync between OneDrive and the local device, and gives you several options for syncing up, down, or simultaneous. The free version lets you sync one pair of folders.