The early Leicas were INVENTED for exactly the purpose you describe OP. There of course have been many other examples for same purpose since then, but rangefinder land is a good place to stay for compact, especially since you can expand into the Ltm Voigtlander and Canon lenses when you're not trying to be super compact. If you're shopping on KEH find a focal length you want and buy it of its in BGN or better, it will perform just fine. Dont forget to check under the non-mfg for voigtlander and canon lenses too. First off I recommend Tamarkin.com. He has a great collection of cheap Leica scremount bodies and lenses that will perform just fine, give him a call and hell do anything to help you find what you're looking for, he's a great guy. Maybe also give Ken Hansen an email, he may have some screwmount. I'd say go with a IIIc (that you know to be working, I had a model missing a light shield inside of it for some reason) or a IIIf, those are good cheap models usually, 250-350 in great condition. I think you'll really have fun with a leica, and it's really ridiculously affordable.