There are SOOOOOOOOOO many Zeiss Ikon folders, I couldn’t cover all of them here (yet), so I’ll cover only a couple that I regularly deal with…
The Zeiss reputation as the “best” folder, probably got started with the 531A, 530, and the 532/16 series.. all of them “Super Ikontas”. If the prefix “Super” is used, it denotes a coupled rangefinder. Until the very late 1950’s, Zeiss’ rangefinder consisted of a stationary or folding arm which held two prisms which rotated as you focused … it also gives the Zeiss Super Ikonta C (and its Russian Mockva 2,3,4, & 5 copies) their distinctive appearance. In general it is tougher to find a really nice solid minty Zeiss Super Ikonta C than most Super Ikontas… same with the Russian copies. BUT, they are usually fitted with the Tessar lens and give excellent results!
The Zeiss Super Ikonta 531A is just a “cute” version of the Super Ikonta C, except this time in 6×4.5. It can be had with a Novar or Tessar Lens, usually f3.5, though it was also fitted with a Schneider Xenar. Really a quality “folder for your pocket!!”
The “Brunhilde” as I call it, of the Zeiss line is the Super Ikonta B, the 532/16 & 533/16. These as SOLID HEAVY cameras compared to most others, they are “tanks,” so to speak. Always fitted with a Tessar, at least I have not seen them with Novar lenses, and usually has a Compur-Rapid shutter (synched) and after 1953, Synchro-Compur shutters. The camera has full auto film wind. Excellent quality, but often show their age and heavy use.
One very under-rated Zeiss folder I think is the so-called “Mess-Ikonta” 524/2 or 524/16. Basically it is an Ikonta B 523 with an uncoupled rangefinder added. The rangefinder is every bit as good as an Isolette III. Lenses for the Mess-Ikonta are often Novars, but they can be had with Tessars as well. Theses are usually found in very excellent condition.