I don't find "Obsession" to stand out in that regard. For some reason, I've always found "The Lights of Zetar" to have the most vivid and vibrant color palette. It must be a combination of rich lighting, a really good batch of Kodak film that week, and possibly new blue and red uniforms (meaning the fabric was freshly dyed and hadn't been to the cleaners much). So I find "Zetar" gorgeous with color saturation, plus it has lots of the Enterprise, no unconvincing "outdoor" set with fake rocks, a guest star I find attractive, and great re-use of music from WNMHGB. At that point, the story only has to be serviceable, and for me it's a damn good show.