In my opinion, a good minimum backup strategy for average users includes a local clone or image of the hard drive onto an external drive that's detached when not in use, updated frequently enough to minimize the pain were the backup needs to be used; coupled with automated network backup to the provider of the user's choice (Backblaze, Carbonite, AWS, etc.).
Cloning provides a more convenient recovery than imaging because no extraction is needed (the clone itself is bootable); but cloning does carry the risks of loss, destruction, or failure, as well as that of a quietly infected or otherwise problematic system being cloned, with no point-in-time recovery option possible. That's one of several reasons why I don't consider cloning to be a complete backup solution.
Imaging provides better security and flexibility because incremental backups and point-in-time recoveries are possible; but the backup will have to be extracted onto the system drive, which is only a minor bother in the big scheme of things, but which does take more time than simply booting from a clone.
Some backup solutions, like
Casper, offer both options. I've been using and recommending Casper (and its Win98 predecessor, Drive2Drive) since it was first written, and it's bailed my own and many of my clients' posteriors out of fires. But until recently, it only included cloning functionality, which I considered more of a downtime-reduction measure than a backup solution
per se. The newest version also offers imaging, however, so you can design quite a good backup solution around it.
One nice, simple, inexpensive approach would be to create a bootable clone of a known-good system, update it frequently, and store it away safely between updates; and also create an image with incremental updates to another destination that's stored elsewhere, either by physically carrying a removable drive elsewhere or by backing it up to the online backup provider of your choice.
That would give you a best-case scenario of a delightfully-easy restore of the entire system from the clone, with easy restore of changes since the last cloning by way of the images. The worst-case scenario would be a more time-consuming restore from the images if the clone were lost, stolen, destroyed, infected, etc.
If the problem is a virus-ridden system drive or some other software problem (as opposed to drive failure), you also have the option of deleting the system drive's partitions using the bootable tool of your choice, booting into the external clone, and re-copying the clone back to the system drive. That would be handy if, for example, you made a clone of your 2.5 inch laptop drive to an external 3.5 inch drive, or if your internal drive is an expensive SSD and your external drive is an inexpensive HDD.
As for the possibility of the images being infected (or held hostage a'la Cryptolocker or similar ransomware), most online backup providers save multiple versions of your backups, so you'd be able to restore from a pre-infection point-in-time. Check with your provider first, however, to make sure.
The above suggestion is just one option, by the way. There are many others. But I like it because it's simple and inexpensive; the vast majority of the time, the initial restore consists of simply swapping the clone into the system and optionally restoring whatever incremental images were made in the interim, if needed; and the ability exists to restore even if the clone drive is lost, stolen, destroyed, etc. It's a simple, cheap approach that covers almost all eventualities.
Rich