Adjustable Bias

If you're curious about comparing Fuji vs Leica lenses on a Fuji body, I did a bunch of comparisons of 50mm options a while back (you don't really want to go wider on a non-Leica body due to distortion in the corners on a sensor that's not prepared for the angle of light coming from a rangefinder lens): http://www.adjustablebias.com/blog/2014/05/19/fuji-x-t1-50mm-portrait-lens-shootout-day-1-xf-56mm-vs-m-mount-leica-summicron-carl-zeiss-voigtlander/ http://www.adjustablebias.com/blog/2014/05/19/fuji-x-t1-50mm-portrait-shootout-day-2-xf-56mm-vs-leica-summilux-m-and-zeiss-c-sonnar/ Ultimately, the older, cheaper (haha, if you can call 1-3k cheaper) Leica lens designs aren't going to hold up against the modern designs from Fuji. Once you get into the newer, top of the line pixel-perfectionist Leica models, they compare quite similarly in terms of sharpness (or at least they both are outresolving the X sensor's limited megapixel count), and you're more making decisions based on your preferences for things like bokeh rendering, size & the availability of autofocus. That said, this is all doing a comparison on a Fuji body. The results of comparing each lens on its own manufacturer's body would likely be different, with many confounding factors as described by other posters.