I use a 35mm Voigtlander Nokton f/1.4. It's decent, especially for close-up work like portraits and such. At greater distance it disappoints a little, but it's a good performer.
Then there's the Nokton f/1.2, of course. You might also consider the Zeiss lenses, which are somewhere in between the Voigtlander/Cosina and Leica.
"Often moments come looking for us". - Robert Frank
"Make good art!" - Neil Gaiman
"...the heart and mind are the true lens of the camera". - Yousuf Karsh