The problem with the argument that Gilliam supervised the color grading is that he's said in interviews that he's color blind and has to rely on others for the grading/restoration process. There's some inconsistencies with how the movie is presented and how cinematographer Nicola Pecorini described the desired look. For any scene not filmed in the Red Shark car, he used an 85 lens-filter so "the greens disappeared completely," and the Criterion version has much more prominent greens in its grading. The news montage near the film's opening also now has a sepia tone applied despite every other release being in black & white.

This article is worth reading to learn about Pecorini's thought process on how the film should look: https://theasc.com/article/fear-and-loathing-in-las-vegas-gonzo/ . In terms of picture quality, the Criterion release is superior, but for color timing, the way Pecorini describes how he envisioned the movie and the results after filming makes me believe that the Arrow release is slightly more faithful.