I have a 90, a 150 soft focus, and a 250. I use the 150 (without the diffusor screens usually) for the most part. I hardly ever use the 90 any more.
While I do landscapes, it's not the wide sweeping, but smaller elements in the scene. The 250 I use mostly for macro. The 150 has worked out just fine for the little portrait work I have done.
I would think which lens could be decided by how much space you have. There isn't a lot of difference (in focusing power) between the 150 and the 180, but if your in a shorter room, the 180 may require more room length. The 150 SF gives the advantage of giving 3 diffuser screens, but you can always add that in the darkroom while printing later.
Don't forget there is also a 140 macro, plus a 127 (I was told this was "the portrait lens" :rolleyes: for my camera, and no I didn't buy it) .