Google Drive and Dropbox could be good options. Both need to generate a token, what I don't like since you have to generate a new one everytime you deploy the app, but it is a good free alternative -they also provide a paid tier.
One of the best alternatives for cloud storage is in my opinion Amazon S3, where you don't need to create a token and just need your credentials. An app example using Amazon S3 could be find here. Another good point is that you can choose the physical location of your "bucket" so you could avoid network latency.