There is the never ending debate which type of backup you should use. The issue is, whichever way you do, you end up losing your data if it’s stolen or compromised in the online servers. The only option that I personally suggest is use an encryption software, that you will use it to store in your external hard drives and store it in your grandmother’s or close relative’s place. So even if somebody over there lays hands on your data they cannot access it without your passwords stored in your brain.
While choosing cloud backup also, ensure the quality of encryption facility they provide, so that even if the company has a security breach, your data is safe. When you have both these features, you can peacefully say, your data is backed up.