M4: 1,5/50 C Sonnar
M4-2: 1,4/40 (or 35) Nokton Classic SC
Alternate lenses frequented:
21mm 3,4 Super Angulon
24mm 3,8 Elmar
35mm Chron ASPH
50mm 2,8 Elmar for near the ocean.
Used more than my SLR's, med format, and large format. No real reason why other than portability.