As long as there is nothing else on the drive that you need to save, then a quick format would much faster and easier than deleting all files and folders. You could then re-clone the boot drive to that drive with the latest files and updates.

An image is usually easier to restore to a new, blank, hard drive after a drive failure, since you would normally use the imaging software's bootable disc to perform the restore and not have to install Windows or another OS to a bare drive first. However, if you are cloning the drive to a spare drive that you already have, and the boot sectors are also being cloned, then you can just swap the drive if the regular boot drive fails and you will only (potentially) lose any new files or updated that were not on the clone.