Originally posted by desertscape You could easily add the 45mm and 75 f/4.5 to your 55mm and have a pretty good landscape setup. Or you could go with the 55-100 zoom since they have come down a lot in price.
My vote is for the 45mm for landscape use and the 165mm LS (as per Tuco's example) for portraiture. Alternatively, either of the 90mm lenses are also good.
I have owned the 55mm lens but became annoyed by its clunky design, stiffness of focusing and overall lack of refined 'feel' compared to e.g. the squat 45mm and the elegant 75mm f2.8AL. That said, I created three of my all-time greatest images with the 55mm back in 2012, but I do not miss it.