Roan vs. FocusFilm
The following captures from Roan and FocusFilm's editions of The Stranger are provided to illustrate the quality points of the the discs. I have attempted to grab the same scenes, but precise shots may be off by a bit.
From this shot, the Roan disc is noticeably sharper and more detailed. Look at the copyright information for an easy example.
These don't look too different, but compare the two Meinekes. The Roan Meineke is sharper and more detailed.
The writing is clearly sharper in the Roan disc in this pair of images.
Overall then, the choice is clear, as the Roan disc has a sharper image than the FocusFilm DVD. The FF version has the Dolby 5.1 remix, Jeffrey Lyon's commentary, and Hearts of Age on its side. See here for a comparison of the FF Trial disc, in the same set, to the Milestone edition of the film.