To me, the Fuji XF18/1.4 is really good. I haven't tried the Voigtlander so I can 't compare. But I feel the Xf18/1.4 is one of the best Fuji XF lenses.
The XF 18/1.4 is really good, no vices and gives clean, crisp images.
It's pretty much in the modern style, no quirks, and sharp across the frame.
It'll make nice sunstars when given a backlit situation and flare is well controlled.
Fuji XF 18mm f/1.4 is about as good as it gets. No it isn't as small as other options, but makes up for it in all other aspects. It is the lens I always reach for if I can only have one lens with me.