I think a review for the paid varieties will be coming in the future, but this review on gHacks goes into a good/reasonable amount of detail and summarizes the test findings in a tabular form which was quite welcome.
The first good sign was that the comparison criteria were clearly stated at the onset, as well as definitions of the various types of backup schemes. Brinkmann also made clear which software was being tested and which wasn’t.
For these reasons, I really recommend his review. He kindly gave me his permission to reproduce his table of results, so without further ado:
Paragon ended up the winner. To quote Martin Brinkmann:
“Even though Paragon Backup & Recovery Free is a lite limited version, it has more to offer in terms of options than any of the other free disk imaging programs that we have tested for this top list. You can use it to create disk images, full, differential and incremental are all supported. Besides saving them in the company's own format, backups can also be saved as virtual disks, The backup software supports password protection and compression, can verify the integrity of archives, and even ships with partitioning options which can come in handy when you connect a new drive to the computer for the first time.”
One con however:
“The program was not able to create a backup of the Windows partition though without a reboot and running the operation prior to the launch of the operating system.”