Dropbox is good and if you have Amazon Prime their photo storage is AMAZING the app syncs with your camera roll on your iPhone and it has unlimited storage. Not sure if you can put other files on it though.
Are you a student? I have two Google Drive accounts with unlimited storage and I think my OneDrive account is unlimited too because they're all included with my university email accounts. If you are, check out what your options are. I like Google Drive.