Man, ghost wife comics have some of the most stunning and also the most disappointing art I've ever seen. I think it really splits between the super detailed, moody webtoons and the more classic manhua styles. For sheer 'can't look away' beauty, 'My Husband's Secret' on Webtoon is the winner for me. The artist uses this incredible watercolor effect for the spectral wife, with layers that make her look both translucent and solid. The modern settings are crisp, but the flashbacks to her past life are all in muted sepia tones with ink washes. It's less about jump scares and more about a haunting, melancholic atmosphere that the art carries perfectly. Another one with surprisingly good art is 'The Ghost Bride Diaries'—the character designs for the male leads are actually distinct, which is rare, and the ghost wife's transformations when she's emotional are creatively creepy, all swirling shadows and fractured light.
That said, you have to wade through a lot of generic art to find the gems. So many series reuse the same big-eyed, small-mouth character models, and the ghost effects are just a basic blue tint. The good ones use the medium to tell the story visually, not just illustrate dialogue.