Not to start a mutual agreement society, but I agree with Roland that the Sonnetar is a much better idea. More contrast, less flare, and sharper. Its user-adjustability is a big plus if you use superspeed lenses with a digital body.
I would be extremely cautious about buying any
lens from the 1950s that has haze; it may not come off. 90/4 Elmars seem to be hit with this, as some Summicrons.
If you plan to use a camera with live view, the Konica 57/1.2 Hexanon (SLR version) - brought on the market in the late 60s is one of the best 1.2 lenses out there. Konica lenses don't have issues with bad coatings or degrading glass (other than when fungus attacks). You might occasionally get cement yellowing (as with a lot of lenses of the era), which if it bothers you can be remedied with mere solar exposure (or a strong UV light).
Originally Posted by ferider
Similar to what Dante said: we already knew 15 years ago that 2 out of 3 samples would haze up over time, but back then these were cleanable. Nowadays, the haze has etched the glass of most lenses - and they are not cleanable any more. There still are clean samples that do not haze up - I feel lucky since I found one 2 years ago. But don't expect to find it cheaply. If you really want it, be generous on the price.
That being said, today, the Sonnetar gives me exactly what I was looking for with the Canon 50/1.2 (character background). Speed, smaller size, faster transmission, and short min. focus are a plus. Maybe interesting for the OP as well ?