I am trying to read a disk with a Venix 80286 file system. I need to copy some files from it.
PartedMagic keeps saying that the partition is "unknown". So, how can I read the files?
No operating system supports all file systems.
Check out this Wikipedia article, the last table shows which OSs support which file systems.
As for which Linux distro is best, they are all equal for all intents and purposes. Files system support is based on kernel version, or with extra software/drivers.