What is "best" depends
entirely on what you're trying to do. I have a suspicion you need data-recovery as much as a disk image... most any basic linux livecd can make a disk image with
dd, but if the disk's in trouble the image will reflect any errors in it too. On the other hand, "smarter" programs which understand the filesystem being copied and don't bother copying empty space may break down completely when they try to digest corrupted data.
I know lots of special-purpose solutions, I tend not to look for or use commercial ones.
Sometimes I use a
udpcast boot-CD to image disks over a network. It's simple, effective, and menu-driven. You can download their basic ISO image, or build your own with all the frills with their web-based ISO generator. You can also boot it over PXE.
I also use Gentoo livecd's for more complex problems, or dying disks. I'm used to the Linux environment, so I'm quite happy with booting a Linux livecd and using the
dd,
dd_rescue(similar to dd, but handles block errors better),
udp-sender/udp-receiver and/or
ntfsclone applications in concert to do what I want.