I have both Sonnars, the 180mm for Hasselblad and the 150mm for Rollei SL66. I prefer the 180mm but I mainly bought this for landscape, architecture and macro shots. This is where it really outperforms the 150mm. Hasselblad also marketed the 180mm as a longer alternative to the 120mm. If you mainly shoot portraits, it is rather a matter of taste. Longer vs narrower field of view. The 180mm is a bit sharper wide open indeed, but with these lenses, it can be hard to hit focus when shooting wide open anyway.