I own about 45 various Retina models, and each of them has its virtues.
As for the "ratchet failure" issue (I am pretty sure people are referring to the steel cocking rack driven by the wind lever) that is largely a myth. Yes, the cocking rack can be damaged, necessitating a repair, but this can only be damaged by winding the lever when the camera is in serious need of servicing (full of dirt and dried grease) or if the camera has reached the end of the roll of film and the user, unaware of this, forces the winding lever in spite of the fact that it doesn't want to go. If you do this, you will definitely damage the cocking rack. Its very hard steel, but it can only take so much abuse.
On the Retina IIa and Ia models, for a period during production, the accessory shoe was attached to the top housing by three screws from the INSIDE of the top cover! They abandoned this practice, favoring screws that went in from outside the cover. It was fairly common for one or more of those screws to work loose if the accessory shoe had been stressed (for example: dropping the camera with a flash attached) and the screws could end up in the gears that drive the cocking rack. If that happens, and the owner forces the winding lever - in spite of evidence that it was jammed - then you grind the screw into the gears and/or the cocking rack, which will also make an expensive repair necessary.
That said, I like all of my Retina cameras, each for a different reason. But for me, the "sweet spot" in the design and manufacture of the Kodak Retina would be the Retina IIa (with rangefinder built in, but no light meter) and to a lesser degree the IIIc/IIIC models, which have both a rangefinder and a selenium meter. On the IIIc/IIIC Retinas, the selenium cell almost always fails or becomes inaccurate, so its kind of arbitrary to choose this model over any other because it has a meter: odds are it won't be reliable. Many people find the IIIc/IIIC to be the best as a user camera, and I do enjoy mine a lot. The larger, brighter viewfinder of the IIIC ("big C") is definitely an advantage when using the camera. All of the lenses are excellent (for the time period, of course. Modern optics exceed the Xenon/Heligon in sharpness and contrast, as you would expect) so there are no "poor lenses" on any of the Retinas. But the early Retinas have a different lens design that has some optical properties that not everyone will appreciate (a bit of rushing at the outer edges when not stopped down, etc.)
A Retina IIa I just finished servicing last week:
