I've got a couple - a Moskva 5 and a Franka Rolfix II. The former has a coupled RF, the latter none at all.

The Moskva, especially when stuck on a tripod is extremely sharp, and cost me less than $20.

The Franka, which is the top spec version of its type, it also pretty good, but not quite as sharp. It is easier to handhold though, and has the benefit of a threaded lens for easier fitment of filters. It has a snapshot setting (hyperfocal distance and f-stop), so can be shot quite quickly.

The East German Ercona II is also quite well regarded, and there are the usual West German folders.

Paul