I had a R4A for a while, never had a problem with it. Also had a Zeiss Ikon, I did have a couple of issues with that, but I bought it second-hand, not new like the R4A.

Personally, if you've got the choice of an Ikon or an R3M, I'd get the Ikon every time, they are more like Leicas in terms of build quality. The M6 is of course a great camera, but I preferred my Ikon.

The Bessas can be somewhat "clunky", but I never had a single issue with regard to usability or reliability, but I'm not the type who thrashes their cameras anyway. I think any of them will serve you well, but if you're like me, and like your cameras a bit prettier, I'd say Ikon or M6. If you want aperture priority, then of course, it's Ikon.