Cosinas can be very reliable but if they fail they may need parts/modules Leicas can be the same but less likely normally shutters can be rebuilt from generic parts. The Cosina LTM &M lenses are solid workhorses.
Originally Posted by Pioneer
Leicas dont need regular service you can use them till they fail- my IIIc not been touched at least since '75, when I bought it, it is near 65 years old.
ContaxII are not uber reliable the ribbons snap regular a Nikon S3 a better shooter.
The Zeiss M is a Cosina module replace camera.
The choice of a rangefinder is do you like the finder? Is the wind on ok?
Subjective things but that is why people buy them.