There are quite a few reviews of backup software online, but most people just seem to read the marketing blurb and then write it out. That's not really helpful. So I searched for the most popular programs and tried them out for myself. Note that I'm using Windows 10 technical preview, an unreleased operating system.

Note that I will keep updating this review as I go, so it may change at times.

Here are my criteria:
 - Provides full, incremental, and differential backup options (mirroring software is not backup software)
 - Robust backups which minimise data loss if corruption occurs
 - Works with Windows 10

Here's what I'm only moderately concerned about
 - Backup performance (it can't be awful, but not too concerned really)
 - Support

Here's what I'm not concerned about at all
 - Price


Let's do the best ones first.

Cobian Backup
This is a free backup program that's has quite powerful and flexible backups.

Likes:
 - Supports multiple backup sets with different settings for source, destination, and compression
 - Keeps multiple versions of files using incremental or differential backup
 - It backs up either to zip, 7z (higher compression), or directory trees if you select no compression.
 - You can select an option to backup each file individually, rather than into a single archive. This will make it more resilient, but can increase the backup size for compressible files.
 - 7z is quite resistant to corruption. If you change a 7z file that has many files inside it you tend to be able to recover the good files.
 - It's quite fast to back up when compression is disabled.
 - Free

Dislikes:
 - When compression is used it's SUPER slow. Backup speeds in the region of 5MB/sec are typical, this is reading an SSD that can do 350MB/sec and writing to a hard drive that can do 150MB/sec. CPU usage of my i7 2600K is 30%.
 - Restore is almost completely neglected, it's basically a manual process. The restore functionality basically doesn't work, but since it creates mirrors and zip/7z files you can do it yourself easily enough. The problem is if you have one full backup then a dozen incremental, and multiple backup sets, this could take a bit of time. It would be easy enough to write a program to automate this.
 - Because backup files are separate if you change a few bytes in a file it will back up the whole file. This means if you edit DNG files metadata you'll have to back the whole thing up again.
 - No support - even the community forums are shut down due to spam

Conclusion: it's a good program, with an awful restore story, but the speed might make it impractical for large data volumes.


AOEMI Backupper Standard
This is a free backup program that's quite flexible.

Likes:
 - Supports multiple backup sets with different settings for source, destination, and compression
 - Keeps multiple versions of files using incremental or differential backup
 - It's really fast - 25MB/sec when compressing, 90MB/sec when uncompressed
 - Effective file and block level deduplication. If you have two copies of a file inside a backup set it only keeps one copy, reducing size. If you modify 10 bytes in a 1GB file the backup size is around 7MB, so very small.
 - Restore is well integrated and is effective
 - Has an effective verify command that works
 - Also backs up system drives and partitions, presumably you this is to back up windows (but I haven't tried it)
 - The free version is effectively fully functional : the paid pro version adds nothing I can see I have any use for
 - You can mount backups as virtual drives

Other factors (not dislikes exactly)
 - Keeps one large file (which you can split to any size you want) rather than a mirror of files. This is less robust but enabled better compression / deduplication.
 - If an incremental backup file is damaged sometimes it won't restore from it. Sometimes it will. If you damage a full backup it tends to cope better. If you damage a file in the header it won't restore at all.
 - There's no option to keep files individual - they always go into a combined backup file.
 - It didn't create a shortcut in the W10 start menu - I may not have selected the right option during setup, unsure.

Conclusion: if you can cope with having your files heaped together rather than individually accessible then I think this one is pretty awesome.


The "Also Rans"
And here are some others I looked at but for various reasons didn't go into as fully.

EaseUs Todo Backup : 
 - EaseUS is pretty decent. I didn't look into it as much as with others because AOEMI is free and does much the same thing. It has a nice interface, full/incremental/differential backups, is fast, provides good support for versions and restores. You can choose compression. If it wasn't for AOEMI this would probably have gotten a lot more attention from me. I may look into it further.

Genie9 Timeline Pro 2015 : this only allows one backup set per computer, to one destination, it's obviously made for non technical users. Otherwise it has the standard required feature set and performance was good. I didn't like that it was always resident in memory because I back up to external disk that I bring in occasionally. Overall not powerful enough.

Genie9 Comprehensive Backup : Fast, multiple backup sets, and all the standard features and a backup file not a mirror. However it crashed during one backup, and it doesn't seem to do deduplication effectively, which is about the only advantage I can see for the big file backup over mirrors. The big killer for me was when I changed the backup file using a hex editor it didn't detect the corruption.

Iperius Backup : doesn't seem to do versioned backups, it's more of a mirror, so I didn't look any further.

NTI Backup Now : couldn't back up to my ReFS formatted disk, so I didn't look any further. It has a standard feature set, but doesn't seem to be able to verify the backup, though it can compare with the source disk.

Vice Versa Pro : Primarily a mirroring / comparison tool. I don't see the capability for versioned backups. Very simplistic interface.

Nova / Novastor Backup : installation ended prematurely, can't install.

Backup Maker : I had a quick look at this. It's free, which is good, and I figured made in Germany means industrial strength. It has full/incremental/differential backup modes, though it gives them consumer friendly names. It's pretty fast. It has compression, but it works as a single setting for every backup and can't be changed per backup. Each backup is its own zip file and because of that it doesn't deduplicate globally. If you have the same file a few times it does reduce the backup size significantly, and as it's a zip file probably works at block level. Because it's a standard zip file it probably handles file corruption better than average. Other than per-backup-set compression levels it's almost as good as AOEMI.

Conclusion and what I'll do
I'm pretty happy with AOEMI for backup of reasonably sized files - documents, graphics, etc, and I'll probably use it. I'll probably use a combination of incremental (store changes since last backup of any type) and differential (changes since last full backup), as I won't want to do full backups all that often, and I'll probably do fairly extensive testing as time goes on.

I'm not comfortable putting hundreds of GB of raw image files into a huge propriety database file though, so for those I'll probably use Cobian Backup to back them up uncompressed and individually, and take the hit in the unlikely event of a restore. This is still better than a simple mirror, as if images are corrupted in any way the original files won't be overwritten.