Another 'go' for the 150mm. While not as sharp as say the 80mm standard, it does produce a nicely smooth look, the typical Sonnar signature. You can really make your subject drown in the surrounding blur. (Whow, I managed to avoid the word 'bokeh'.)
You may also consider a black 150mm C T*. Those are optically identical to the CF but go for less.
I agree with Slixtiesix above that the 160mm Tessar is very nice in handling but not as cool optically, not the same softish drowning effect.
Good luck with your choice.