I guess there are as many replies to this thread as there are Hasselblad lens combinations :-).
Having said that, nobody has thus far mentioned my combo, which is 50mm, 80mm, 120mm, 180mm. As has been mentioned previously, the 120mm is a spectacular performer and is great for full length to 3/4 portraits. The 180 is great for head shots. I have never personally felt a need for the 250mm. But if portraiture is your thing, as it is for many who use the blad, the 120mm/180mm combination will obviously offer great options.