I quite enjoy the Nokton 35 1.4 MC. I also own the Leica Summilux 35 ASPH v1.
For me, I typically use the Nokton as a wide portrait lens. My style is close and personal photography, so focus shift within the first meter is incredibly important to me, especially when using maximum aperture.
Yes, the Nokton is softer in the corners than the Summilux, and yes there is swirly bokeh wide open. However, I feel this adds to the romance in the photo, and is particularly pleasing for portrait photography.
I've read, and agree, that the Nokton is most similar to the Summilux 35 PRE-ASPH, with more enhanced resolution than the original 'lux.
While the other lenses mentioned in this thread are great suggestions, I personally have experience with the Nokton 35 1.4 MC and have been quite pleased with my purchase. It's my standard lens cap for my Leica M6TTL.