I have the early-80s 90/2 Summicron (49mm filter thread) with the hood that Tom hates because it slides over the aperture ring. For some reason the hood doesn't bother me. I really like the lens because I have long fingers, and the focus ring is a little farther back than on the later model. I mostly use it in the theater and concert hall, and use a light little CV 90/3.5 for outdoors. But on one trip, I travelled with the Summicron, and was stunned by how good it is at all apertures. Maybe I got a good one, but I'm very happy with it
I once shot some test slides on a firm support with both my 90 'Cron and a chrome Nikkor 85/2. The Summicron is a bit better wide open overall, and significantly better getting towards the edges of the frame at all stops. The Nikkor is a bit better at f/4 (it peaks early). The Nikkor does have very harsh double-line bokeh at wide stops. The main reason why I sold it in favor of the Summicron was that it was very, very heavy, so I didn't ever want to carry it around. The black Nikkor does not have the weight issue, but it will cost you as much as many used Summicrons these days
I once had a very good Jupiter-9, but it only focused properly at 8 feet and beyond. The Nikkor was of similar character, but contrastier. I also tried two other J-9s that were terrible.