I use my paid product "Acronis True Image 2011" program for Cloning and "Macrium Reflect" free program for Imaging.
I like Acronis for cloning since it clones my HDD faster than Macrium.
I prefer Macrium for Imaging since I like its user interface a little better than Acronis.
I've used both products to Clone and Image since I like to be familiar with a couple of Backup programs in case I encounter problems with one of the programs.
I've also used "Clonezilla" for Cloning and Imaging. I rarely use it as it's a 3rd-choice program and it can be a little confusing for novice users with more "command prompt" dialog screens vs "Windows" type dialog screens that are used for many other Backup programs.
With Acronis, you can automate a wide variety of backup schemes. Some of the free Backup programs offer automated scheduling as well.
I use Acronis to Clone periodically and I also have a twice-daily automated backup that copies specific items to my external HDD.
As Didier Stevens mentioned, the compression rate will vary dependent on the type of files that are being backed up, particularly when full-HDD Imaging is performed.
I recently moved my video files and most of my photos/picture items to a 2nd internal HDD. By doing that, I reduced my "C" HDD cloning time (using Acronis with Sata III speed) from about 45-50 minutes to about 12-15 minutes
This is convenient for me since I have a fast recovery method for my OS HDD in the event that problems are encountered (malware, OS issues, user error, bad download's, failed HDD).
Redundancy is a good strategy with backups, having multiple copies in multiple locations as that should protect you against most malicious scenarios such as ransomware, delayed encryption infections, etc.