Zeiss Sonnar Opton 50mm f/1.5,
I grant you that the Opton Sonnar is a wonderful lens, but the Opton was never made in LTM.
The wartime Jena lenses were never DESIGNED for LTM, but were shoe-horned into a focus mount, and usually never performed acceptably, being impossible to calibrate for a normal working range. Few lenses were made well enough to last very long (hand filed parts of soft aluminum, and so on, due to nightly bombing and shortage of material). Lenses which survived the war are few, and have 63 years of use to be overcome. The other LTM Sonnars have their OWN problems.
On the OTHER hand the Nikkor and Canons were made under ideal circumstances, and were designed exceedingly well for their purpose.
I know quite a few printers who have a Summicron DR on their enlarger.
Silly choice because the DR Summicron is EXACTLY the same as a plain vanilla Summicron of the '50s, just in a mount that will focus more closely. But back in the dark ages, there was a legend that any imperfections the taking lens imparted on the negative would be removed if the image were printed THROUGH the same lens to print it. Actually, lots of folks used their taking lens to print with because enlarging lenses were expensive and in short supply after WW2 and the early '50s. As late as the '70s, though, taking lenses were used to make big prints, 16x20 or bigger, for their correction might be as good or better than Focotar or Coponon: both types of lenses were out of their design ranges. Leica suggested the 2.8 Elmar as the best choice. By the mid '70s, though, normal enlarging lenses were better than taking lenses at the higher range --- today there is no comparison.