https://jlelse.blog/posts/migrated-to-onedrive
For me, there is no ideological element to where I choose to store my backups. Thanks to PGP, you can get the same degree of privacy anywhere. In this respect, OneDrive is a perfectly good choice.
These days, though, I'm using BorgBackup, which unfortunately rules out the cheapest options (b2, OneDrive, and so on), but offers some unique features in return.