On the M9, besides the lenses already mentioned, I toughly enjoyed and liked the look and performance of the Leica Summilux 35mm f1.4 asph pre FLE. It had a wonderful combination of being a bit painterly when shot wide open and somewhat forgiving while still rendering a high degree of detail without being bitingly sharp. The current LLL 35mm f1.4 AA would be a good substitute with similar attributes.
