I think the 55 mm is a nice focal length and so are 58, and 60. Upon first glance these might seem to be too close to be of any real significance but in actual practice there is quite a bit of difference between 50 which is actually about 48.1 as I recall for most older Nikon lenses marked "50mm", and 55mm.
Early on in my 35 mm SLR life I had a Russian made Zenit with a 58 mm lens, and Nikon used to make a 58 mm lens,allegedly to give both eyes open, one to one life size viewing through the pentaprism of the Nikon f. A few years ago the Cosina brand released a 58 mm and once again Nikon is now making a 58 mm, an auto focus model that has a hefty price tag, but which makes beautiful pictures.
You are about the only person I know that likes the 43 to 86 mm zoom lens, but I have heard that the later generation models were really not that bad and that it was the early generation models which were widely criticized, and were the culprit in bringing that lens model's reputation down, similar to the way that the old Nikon 200 mm f/4 chrome barrel was a poor performer but the AI and AI-s models were actually quite decent.