I found a collapsible Summicron (version 1), which didn't have a damaged front element, and after service by Don Goldberg, it is a great lens. Moderate contrast (people say low, but I don't see this), no distortion. It is a lovely lens, with wonderful rendering. If you get a SOOKY close-up adapter for your Leica III, then you have the equivalent of the DR lens. The equivalent for the M3 is the SOMKY. However, the front lens glass and coating of this lens is extremely soft, and it is hard to find an undamaged one. This lens requires a UV filter to prevent damage to the front element glass. I don't have experience with the other lenses that you mention. If you find this lens with an intact front element, then it is worth getting.
Other options that you may consider are the Voigtlander Heliar 50mm f/2 or f/3.5 LTM lenses. These are modern, and very sharp. However, at f/2, that lens has a bit of veiling flare and spherical aberration that makes it wonderful for portraits.
I also have a Jupiter 3+ LTM, which is the modern remake of the Zeiss Sonnar 50mm f/1.5. Classic, yet modern at the same time. Very small too, for an f/1.5 lens.