I have been playing around with an Edixa Prismaflex for a bit over a year now:
Edixa Prismaflex by
berangberang, on Flickr
I think it could justifiably be called the most "useable" of the old German SLRs... but useable and "good" are two different things. It takes M42 lenses and it works, and that's about all I can praise it for. I've taken one entirely apart to reglue a detached shutter curtain and it was by far the simplest (focal plane shutter) SLR I have ever disassembled, although I admit I still do not fully comprehend the instant mirror return system (which had to be designed to skirt around Pentax patents presumably).
exa by
berangberang, on Flickr
The Exa is probably the only bomb proof SLR. No shutter curtains to wrinkle, tear, or hole. In fact it barely has a mechanism in it at all. Later models are a bit less well made, but will take M42 lenses and adopted a lever wind which makes them a bit less fussy to handle. The only downside is the top shutter speed of 1/150. The Exa series remained the cheapest SLR one could buy for years - maybe even decades.
The Exaktas are fine cameras -up until the 1960s. The 1950s Exaktas cost as much as Leicas at the time, and the fit and finish is comparable. In the 1960s Exakta became entangled in all sorts of trademark litigation and the company seemed to focus more on driving down costs instead of building the best SLR possible. The very worst of the Exaktas, quality wise in my experience are the last ones - the VX 1000 and VX 500. My VX 1000 was basically sub-Praktica quality. The one good thing about the VX 500/1000 is the short throw advance lever, which was adopted way too late in Exakta history. The earlier exaktas have an almost ludicrous lever throw to advance the film.
The VX IIa is probably the Exakta to watch for. It was made before quality went down the drain, has modern PC flash sockets, and looks gorgeous. Perhaps the most beautiful SLR ever made. The Schneider Xenon and CZJ Pancolar are two great lenses for these old cameras.
Here's my crappy VX1000:
Exakta TL VX1000 by
berangberang, on Flickr
The RTL 1000 that followed is not a bad camera despite its reputation. I would say it is probably a better camera the VX 1000.
In the west there was also the Zeiss/Voigtlander Icarex, I have not used one but they look nice enough. In any event it's probably more reliable than its leaf shuttered brethren, and it can take real lenses.
😉