Occording the the commentaries by Ridley Scott, James Cameron and Jean-Pierre Juenet on the SE DVD's
The 1979 theatrical version of Scott's ALIEN is his actual Director's Cut, depsite the fact that Fox gave his 2003 re-release the "director's cut" moniker.
The 1991 Special Edition of ALIENS is Cameron's preferred version. Although he does'nt despise the 1986 theatrical cut.
The 1997 theatrical version of ALIEN RESSURECTION is Jeunet's final cut. The 2003 Special Edition version was simply an added DVD bonus for fans of the film.