I don't know about other regions, but the new R1 Restored Directors Cut is coming out soon. It promises to have better vid quality than the previous lackluster Directors Cut, as well as a commentary with Mann.
The only DVD of the original theatrical version of the film is the OOP UK DVD from BMG.
All the other versions have been messed about with to one degree or other. The forthcoming Anchor Bay disc (and the UK version, from Momentum) are the official "Director's Cut".
The R2 BMG dvd is well worth getting hold of, as it's a surprisingly good transfer for the time. Sure, it's non-anamorphic, but the video master doesn't appear to be some horrible composite-video leftover from LD, so the picture quality is vibrant and detailed, with no real compression problems. The PCM stereo soundtrack has a nice texture to it as well.
IMO this disc (alongside Anchor Bay's existing versions and the upcoming Director's Cut) would make up a fine Manhunter dvd collection, as you'd have numerous cuts of the movie plus some decent extras. Although I do hope that the picture quality of the R1 DC is better than that of the R2 DC.