Please, unless absolutely necessary, always use Disk Copy 4.2 the software itself), and not any later version, for floppy disks. It does not matter if they're 800K or 1.4MB.
ALL versions of Disk Copy 6 (except 6.0.x, which is not recommended because of its weird compression schemes, and because it was never supported by Apple), omit important data from the floppy disks.
I'm referring to the software, not just the format — use of Disk Copy 6.x in DiskCopy 4.2 "mode" doesn't count — the data is still omitted.
DART will also create good images, but I don't recommend it because its compression scheme is very obscure.
For non-floppy disks, Disk Copy 6.x is fine, though Toast also works.