Ahh yes. Back before Nikon V. Canon for world domination.
Like you, I fall into the Contax camp. I have two Contax IIas and a Kiev IIa (Contax II clone). Use the Opton Sonnar 50 1.5 and postwar Jena Sonnar 50/2. Also have an early Jupiter-8 that's a fine performer.
I have had both of my Contaxes CLA'd. That said, the first one, also built around 1951, I had CLA'd, but it was working fine (the shutter worked fine, anyway, rangefinder was accurate but hazy). The repairman said it looked as if it had never been serviced and he was the first to take it apart. The second one, an even earlier specimen, was fortunately repaired by a very kind and knowledgeable gentleman who roams these forums.
I've never owned a leica camera although I have two of their enlargers.
I think the pre-war and post-war Contax cameras are far superior to the Leica III, because of the rangefinder/viewfinder accuracy and ease of use. The shutter design is much more complex, however, so if it ever does stop working, finding someone to repair it and do the job well is a bigger task than it would be to find someone to repair the Leica III. I think the inventiveness and engineering that went into the Contax design is what led Leica eventually to design its M-series.
The Kiev and Contaxes are my favorite cameras to use. I wish there was some way to take the controls and shutter from a Contax IIa and put them on a pre-war Contax II with its rangefinder and viewfinder and slightly larger body, which seems to fit my hands better.
Anyway, there's my 2 cents and then some. Maybe 5 cents.