I'd say convenience and shareability. I come across far more dead Dropbox links than dead Google Drive links.

And Onedrive is further down in enshittification than Drive. Like windows relentlessly trying to reenable and reinstall without permission.

Overall I like it cause it's just there and works. But I wholeheartedly would not recommend it for business applications (without backups at least). There have been instances of companies data just getting deleted or randomly banned from their google account.

In essence, I would not pay for upgraded storage.