The lower egress fees are super nice, but until someone can beat the Glacier Deep Archive pricing @ $0.00099 per GB I'm going to keep using that.
I'm not even talking backups here, if you need a backup at all, you probably need it ASAP. This is a governance product.
Cloudflare brings R2 to the edge.
Egress is the cost that prevents that.
Archive is great for archiving. S3 standard tier is not for archiving.
So for backups, stuff you don't need often (AND don't need to restore quickly), it's fine. Not so for most other use-cases.