I suggest the Zeiss Ikon "Super Ikonta" (531/2). It's been in production until (relatively) lately so you can find units in extremely good conditions. The telemeter is very effective if well tuned up. If you choose one with Tessar/Compur combination, you'll have a setup which can almost compare to today's standards. Plus, I find the 6x9 to 4,5x6 reducing mask an amusing idea (that's not available on units with "Novar" lenses).

I bought it basically without a reason, just because it reminded me of my grandpa's camera. Probably the idea of taking pictures with a Tessar fascinated me. Now I find myself using it in every occasional trip in which I have to travel light, and of course on every hike over the Alps.