Warning: huge major bias! I am a developer of Macrium Reflect, so please bear in mind that what I'm discussing is probably influenced by that!
Live CD is preferred over shadow copying. (I think.) Ideally I would just download and burn a CD iso image and work off of it without having to install anything on Windows.
Well, Macrium Reflect runs via VSS (the Volume Shadow Copy Service). We do this because it gives us a number of advantages in that Microsoft maintain and support it. The alternative to this would be inserting a custom driver into your kernel to do copy-on-write style backup. Such things can cause interoperability problems between drivers and platforms etc, and our principle is not to destabilise your system (although for when VSS is disabled, our driver does work :)). Other services can be configured to interoperate with it and allow us to back them up, which we're currently working on.
That said, Reflect does come with a live CD product. In fact it comes with two - both a PE/WAIK based environment (Windows) which features the full product and a Linux live CD, which has slightly fewer features. Mostly, our workflow is focused on using the Live CD to restore your system; however, the PE disk can also image it.
Our restore functionality should restore your system to full working order, including booting - however, this isn't always possible. Specifically, your master boot record can be overwritten by third party software for a variety of reasons - disk encryption, custom bootloader etc. Reflect has the option to restore/replace whatever your MBR has with BCD (Vista and later bootloader) - so providing the image is successfully written down, we should be able to fix any boot problems that have arisen.
There are other ways to achieve a full disk image. You can use
dd to literally take a copy of all the bytes on the disk and write them elsewhere, including to a file. Obviously, doing this will take a copy of every byte, regardless of whether it is necessary (i.e. in use, according to the file system's MFT) - whereas a lot of imaging software including ours will look at what active sectors you're using, and only copy those. This makes your backup much, much smaller and is the default behaviour in Reflect.
Ability to work with (include writing to) NTFS file systems without any problems. (A few years back when I played with Linux, NTFS support was not adequate.
My experience with Linux and NTFS has been mixed as well; I used to dual boot with ntfs-3g when it was in beta and had some interesting experiences (like non-bootable Vista systems). These days I find it is much more stable.
Reflect's NTFS support is fairly mature now. We've a fair number of customers who are using our product regularly to back up their disks and we've seen a lot of different configurations, setups, highly fragmented disks... etc.
I can't really speak for the other imaging products our there as I just don't know them very well - I'm actually quite new to this space myself.
Other considerations you might like to look at, especially if you're paying:
- Does the software support GPT/EFI boot disks? There are increasing numbers of users with EFI bootable systems and this is a different setup to the MBR that imaging software must respect.
- Can the imaging software do differential/incremental backups? If you're running regular or automated backups, you might want to design your strategy for backing up in such a way that your daily backups take less space.
- Does the live CD / other recovery options work as advertised with your hardware.
As always, I'd still say try a few and see what fits your needs :)