Another vote for Arq if what the OP wants is backup. This lets you pick and switch storage providers. I don't think you should plan on staying with any provider for more than 2-3 years, the landscape changes too fast. Arq lets you be independent.
You lose Arq, you lose your backups.
https://www.arqbackup.com/s3_data_format.txt
And there are tools to help: