Go for SysV r4. Always. It is absolutely the best. No doubt about it.
Be sure you get the October 18 1988 original. The rest is horribly bloated.
(hint: be more specific, and maybe others will too)
that reminds me. I have a box or orifinal AT&T install disk of this for
the 386 platform, LESS the first install floppy.
Does anybody have images of these disks?
I'm tempted to try it out again on some old 486 for the hell of it.